Grade Level

Moons of Jupiter

Sunday September 1, 2013

On a clear night when Jupiter is up, you’ll be able to view the four moons of Jupiter (Europa, Ganymede, Io, and Callisto) and the largest moon of Saturn (Titan) with only a pair of binoculars. The question is: Which moon is which? This lab will let you in on the secret to figuring it out.

You get to learn how to locate a planet in the sky with a pair of binoculars, and also be able to tell which moon is which in the view.

Materials

Printout of corkscrew graph
Pencil
Binoculars (optional)

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Download Student Worksheet & Exercises

Look at your corkscrew satellite graph. These are common among astronomers for both Saturn and Jupiter. Notice how Saturn has a lot more wavy lines than Jupiter. We’re going to focus on Jupiter for the first part of this lab. Jupiter’s graph is the one on the left with Ganymede as one of the moons.
The wavy lines represent four of Jupiter’s biggest moons: Ganymede, Callisto, Europa, and Io. The central two lines for a band is the width of Jupiter itself. If you see any gaps in the wavy lines, those are times when the moon is behind Jupiter. Each bar across that corresponds to a number is an entire day. The width of the column represents how far away each moon is from Jupiter. Notice at the top it says East and West.
Draw a circle that represents Jupiter.
Notice the largest waves are made by Callisto. Who makes the smallest waves? (Io.)
Look at Dec 4th. Which moons are on which side of Jupiter? (Ganymede is the furthest east, and Io is closer to the planet, still on the east side. On the west, Europa is closer to Jupiter than Callisto.)

What’s Going On?

Jupiter’s Rings and Moons

Jupiter’s moons are threadlike when compared with Saturn’s. Also, unlike Saturn’s rings, Jupiter’s rings come from ash spewed out from the active volcanoes of its moons. Since Jupiter is so large, its gravity likes to catch things. When a volcano shoots its ash-snow up, Jupiter grabs it and swirls it in on itself. The moons are constantly replenishing the rings, which is why they are so much smaller than Saturn’s and much harder to detect (you won’t see them with binoculars or a backyard telescope).

If you’re doing the binocular portion of this lab in the evening, the numbers on binoculars refer to the magnification and the lens at the end. For example, 7×50 means you’re viewing the sky at 7X, and the lenses are at 50mm. Most people can easily hold up to 10x50s before their arms get tired. Remember, you’re looking up, not out or down as in normal terrestrial daytime viewing.

Saturn’s Rings and Moons

Galileo Galilei was the first to point a telescope at the sky, and the first to glance at the rings of Saturn in 1610. In the 1980s, the Voyager 1 and Voyager 2 spacecraft flew by, giving us our first real images of the rings of Saturn. Some of the biggest mysteries in our solar system are: What are the rings made up of, and why?

The Cassini-Huygens Mission answered the first question: The rings are made of billions of particles ranging from dust-sized icy grains to a couple of mountain-sized chunks. Actually, Saturn’s rings are an optical illusion. They are not solid, but rather a blizzard of water-ice particles mixed with dust and rock fragments, and each piece orbits Saturn like a little a moon. These billions of particles race around Saturn in tracks, and are herded into position by moons that also orbit within the rings (“shepherd” moons). Shepherd moon Pan orbits in the Encke gap, Daphnis orbits in the Keeler gap, Atlas orbits in the A ring, Prometheus in the F ring, and Pandora in the F ring. These moons keep the gaps open with their gravity.

The second question is harder to answer, but the latest news is that the rings are pieces of comets, asteroids or shattered moons that broke apart before they ever reached Saturn. Although each ring orbits at a different speed around the planet, the Cassini spacecraft had to slow down to 75,000 mph before it dropped into the rings to orbit around the planet.

While the rings are wide enough to see with a backyard telescope, the main rings (A, B and C) are paper-thin, only 10 meters (33 feet) thick.

Uranus and Neptune are called ice giants because of the amounts of ice in their atmospheres. Their atmospheres are also made of mostly hydrogen and helium.

Cassini found that a great plume of icy material blasting from the moon Enceladus is a major source of material for the expansive E ring. Additionally, Cassini has found that most of the planet’s small, inner moons appear to orbit within partial or complete rings formed from particles blasted off their surfaces by impacts of micrometeoroids.

Exercises

Find a date that has all four moons on one side of Jupiter.
When is Callisto in front of Jupiter and Io behind Jupiter at the same time?
Are the images you’ve drawn in the table what you’d expect to see in binoculars, or are they upside down, mirrored, or inverted?

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Star Charting

Sunday September 1, 2013

If you want to get from New York to Los Angeles by car, you’d pull out a map. If you want to find the nearest gas station, you’d pull out a smaller map. What if you wanted to find our nearest neighbor outside our solar system? A star chart is a map of the night sky, divided into smaller parts (grids) so you don’t get too overwhelmed. Astronomers use these star charts to locate stars, planets, moons, comets, asteroids, clusters, groups, binary stars, black holes, pulsars, galaxies, planetary nebulae, supernovae, quasars, and more wild things in the intergalactic zoo.

How to find two constellations in the sky tonight, and how to get those constellations down on paper with some degree of accuracy.

Materials

Dark, cloud-free night
Two friends
String
Rocks
Pencil

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Download Student Worksheet & Exercises

Tape your string to the pencil.
Loosely wrap the string around your finger several times so that the tip of the pencil is about an inch above the ground.
Find a constellation. Point to a star in the constellation.
Have a second person place a rock under the pencil tip.
When they’ve placed the rock in position, point to another star.
Have a second person place a rock under the pencil tip again.
Repeat this process until all the stars have rocks under their positions.
You should see a small version of the constellation on your paper.

What’s Going On?

People have been charting stars since long before paper was invented. In fact, we’ve found star charts on rocks, inside buildings, and even on ivory tusks. Celestial cartography is the science of mapping the stars, galaxies, and astronomical objects on a celestial sphere.

Celestial navigation (astronavigation) made it possible for sailors to cross oceans by sighting the Sun, moon, planets, or one of the 57 pre-selected navigational stars along with the visible horizon.

Watch the video that shows how the stars appear to move differently, depending on which part of the Earth you’re viewing from. What’s the difference between living on the equator or in Antarctica (explained in video)?

The first thing to star chart is the Big Dipper, or other easy-to-find constellation (alternates: Cassiopeia for northern hemisphere or the Southern Cross for the southern hemisphere). The Big Dipper is always visible in the northern hemisphere all year long, so this makes for a good target.

Use glow–in-the-dark stars instead of rocks, and charge them with a quick flash from a camera (or a flashlight). Keep your hand as still as you can while the second person lines the rock into position. You can also unroll a large sheet of (butcher or craft) paper and use markers to create a more permanent star chart.

Exercises:

If you have constellations on your class ceiling, chart them on a separate page marking the positions of the rocks with X’s.
Tonight, find two constellations that you will chart. Bring them with you tomorrow using the technique outlined above in Experiment.

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All About Kidneys

Thursday August 15, 2013

Although urine is sterile, it has hundreds of different kinds of wastes from the body. All sorts of things affect what is in your urine, including last night’s dinner, how much water you drink, what you do for exercise, and how well your kidneys work in the first place. This experiment will show you how the kidneys work to keep your body in top shape.

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Materials

1 liter of water per student
1 can of soda per student
1 sports drink, like Gatorade, per student
Red food dye
Chalk (or a handful of sand)
Coffee filter or cheesecloth
pH paper strips
Disposable cups
Clean glass jar
Rubber band
Measuring cups

If you are doing the optional Third Bonus Experiment:

solution your teacher has prepared for you
pipe cleaners
cleaned out jar or bottle (pickle, jam, or mayo jar)
water
borax

Download Student Worksheet & Exercises

Experiment

First Experiment: How Quickly Do the Kidneys Process Fluids?

Drink a liter of water quickly (in less than five minutes).
Wait 20 minutes (you can start on the second part of this lab while you wait) and then collect your urine in a disposable cup in the bathroom and use a pH testing strip to test the pH by dipping it in the cup.
Repeat four times so that you have four samples collected 20 minutes apart.
Repeat steps 1-3 for two different liquids, such as a sports drink and a soda.
Complete the data table for all three liquids.

Second Experiment: Kidney Filtration

Crush a piece of chalk and place it in a clean glass jar. (You can alternatively use a handful of sand from the playground if you don’t have chalk.)
Fill the jar partway with water.
Add a few drops of red food coloring to the water.
The chalk (or sand) represents toxins in the blood. The water represents the blood.
Place a coffee filter (or cheesecloth) on top of the jar and secure with a rubber band. This coffee filter is your kidney.
Tip the jar over a disposable cup and pour the contents into the disposable cup. This is the kidney filtering the blood.
Observe what the filter traps and what it doesn’t and record your observations in the data table.

BONUS Third Experiment: Kidney Stones

A kidney stone is something that develops in the urinary tract from a crystal. Crystals start from “seed crystals” that grow when placed in the right solution.
Use a pipe cleaner to create a shape for crystals to cling to (suggestion: cut into 3 lengths and wrap around one another). Curl the top pipe cleaner around a pencil, making sure the shape will hang nicely in the container without touching the sides.
Add 2 cups of water and 2 cups of borax (sodium tetraborate) into a pot. Heat, stirring continuously for about 5-10 minutes. Do not boil, but only heat until steam rises from the pan.
When the borax has dissolved, add more, and continue to do so until there are bits of borax settling on the bottom of the pan that cannot be stirred in (It may be necessary to stop heating and let the solution settle if it gets too cloudy). You’ll be adding in a lot of borax! You have now made a supersaturated solution. Make sure your solution is saturated, or your crystals will not grow.
Wait until your solution has cooled to about 130^oF (hot to the touch, but not so hot that you yank your hand away). Pour this solution (just the liquid, not the solid bits) into the jar, and add the pipe cleaner shape. Make sure the pipe cleaner is submerged in the solution. Put the jar in a place where the crystals can grow undisturbed overnight, or even for a few days. Warmer locations (such as upstairs or on top shelves) are best.
NOTE: These crystals are NOT edible! Please keep them away from small children and pets!

Kidneys Process Fluids Data Table

Record the pH and volume (did you urinate a lot, medium, or little?)

Drink Type	20 min	40 min	60 min	80 min

Urine tests look at different components of urine. Most urine tests are done to get information about the body’s health and clarify problems that it might be having. There are over 100 different kinds of urine tests that can be done. Depending on the test, scientists look for different things.

The most obvious, and the one you can do yourself at home, is to look at the color of urine, which is normally clear. Many different things affect urine color, and the darker it is, the less water there is in it. Vitamin B supplements can turn it bright yellow. If you like to eat blackberries, beets or rhubarb, then your urine might be red-brown.

The next thing to check is smell. Since urine doesn’t smell much, it’s a signal if it suddenly takes on an unusual odor. For example, if you have an E. coli infection, your urine will take on a bad odor.

Scientists also check the specific gravity, which is a measure of the amount of substances in the urine. The higher the specific gravity number measures, the more substance is in the urine. For example, when you drink a lot of water, your kidneys add that water into the urine, which makes for a lower the specific gravity number. This test shows how well the kidneys balance the amount of water in urine. The specific gravity for normal urine is between 1.005-1.030.

pH is a measure of how basic or acidic something is, and for a urine test, it’s the pH of the urine itself. A pH of 7 is neutral, a 9 is strongly basic, and a 4 is strongly acidic. Using a strip of pH paper will tell you how basic or acidic your urine is. Normally, pH is between 4.6-8.0 for urine.

Protein is not supposed to be in the urine, unless you’re sick with a fever, just had a hard workout session, or are pregnant. Scientists look for protein to be present in the urine to detect certain kinds of kidney diseases.

Glucose is sugar in the blood, and usually there’s no glucose in urine, or if there is, it’s only a tiny bit. When scientists detect glucose in the urine, it means that the body’s blood sugar levels are very high, and they know they need to look into things further.

When scientists find nitrites, they know that bacteria are present, especially the kind that cause a urinary tract infection because bacteria make an enzyme that changes nitrates to nitrites in the urine.

Strong, healthy people will have a couple of small crystals in their urine. If scientists find a large number of crystals, then they start looking for kidney stones. If they don’t find kidney stones, then they start looking at how the body metabolizes food to see if there’s a problem.

Most adults make about 1-2 quarts of urine each day, and kids make about 0.6-1.6 quarts per day

Kidneys Filtration Data Table

Amount of Chalk or Sand	Amount of Water	Color of Water after Mixed	Amount of Solids Filtered Out by Cheesecloth

Questions:

Which fluid produced more urine for the first experiment?
Did the caffeine solutions cause the calcite stones to shrink or have no effect?
What does pouring the chalky water through a coffee filter show?
What are kidney stones and how are they formed?

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Cosmic Ray Detector

Thursday August 1, 2013

When high energy radiation strikes the Earth from space, it’s called cosmic rays. To be accurate, a cosmic ray is not like a ray of sunshine, but rather is a super-fast particle slinging through space. Think of throwing a grain of sand at a 100 mph… and that’s what we call a ‘cosmic ray’. Build your own electroscope with this video!

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Materials:

Clean glass jar with a lid
Wire coat hanger and sand paper
Aluminum foil
Vice grips or a hacksaw
Scissors
Balloon or other object to create a static charge
Hot glue gun (optional)

Download Student Worksheet & Exercises

Troubleshooting: This device is also known as an electroscope, and its job is to detect static charges, whether positive or negative. The easiest way to make sure your electroscope is working is to rub your head with a balloon and bring it near the foil ball on top – the foil “leaves” inside the jar should spread apart into a V-shape.

Exercises

How does this detector work?
Do all particles leave the same trail?
What happens when the magnet is brought close to the jar?

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Phases of the Moon

Monday June 24, 2013

The Moon appears to change in the sky. One moment it’s a big white circle, and next week it’s shaped like a sideways bike helmet. There’s even a day where it disappears altogether. So what gives?

The Sun illuminates half of the Moon all the time. Imagine shining a flashlight on a beach ball. The half that faces the light is lit up. There’s no light on the far side, right? For the Moon, which half is lit up depends on the rotation of the Moon. And which part of the illuminated side we can see depends on where we are when looking at the Moon. Sound complicated? This lab will straighten everything out so it makes sense.

Materials

ball
flashlight

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This first video will show you how the moon changes it’s appearance over the course of its cycle:

This video will show you how to demonstrate why the moon changes it’s appearance over the course of its cycle:

Download Student Worksheet & Exercises

This lab works best if your room is very dark. Button down those shades and make it as dark as you can.
Assign one person to be the Sun and hand them the flashlight. Stay standing up about four feet away from the group. The Sun doesn’t move at all for this activity.
Assign one person to be the Moon and hand them the ball. Stay standing up, as you’ll be circling the Earth.
The rest of the people are the Earth, and they stand or sit right the middle (so they don’t get a flashlight in their eyes as the Moon orbits).
Start with a new Moon. Shine the flashlight above the heads of the Earth. Move the Moon (ball) into position so that the ball blocks all the light from the flashlight. Ask the Earth kids how much light they can see on their side of the Moon (should be none). Which phase of the Moon is this?
Now the Moon moves around to the opposite side of the Earth so that the Earth kids can see the entire half of the ball lit up by the flashlight. Ask the Earth kids how much light they can see on their side of the Moon (should be half the ball). Which phase of the Moon is this?
Now find the positions for first quarter. Where does the Moon need to stand so that the Earth kids can see the first quarter Moon?
Continue around in a complete circle and fill out the diagram. Color in the circles to indicate the dark half of the Moon. For example, the new Moon should be completely darkened.
Now it’s time to investigate why Venus and Mercury have phases. Put the Sun in the center and assign a student to be Venus. Venus gets the ball.
Venus should be walking slowly around the Sun. The Sun is going to have to rotate to always face Venus, since the Sun normally gives off light in every direction.
The Earth kids need to move further out from the Sun than Venus, so they will be watching Venus orbit the Sun from a distance of a couple of feet.
Earth kids: What do you notice about how the Sun lights up Venus from your point of view? Is there a time when you get to see Venus completely illuminated, and other times when it’s completely dark?
Draw a diagram of what’s going on, labeling Venus’s full phase, new phase, half phases, crescent, and gibbous phases. Label the Sun, Earth, and all eight phases of Venus.

Reading

The Sun illuminates half of the Moon all the time. Imagine shining a flashlight on a beach ball. The half that faces the light is lit up. There’s no light on the far side, right? So for the Moon, which half is lit up depends on the rotation of the Moon. And which part of the illuminated side we can see depends on where we are when looking at the Moon. Sound complicated? This lab will straighten everything out so it makes sense.

One question you’ll hear is: Why don’t we have eclipses every month when there’s a new Moon? The next lesson is all about eclipses, but you can quickly answer their questions by reminding them that the Moon’s orbit around the Earth is not in the same plane as the Earth’s orbit around the Sun (called the ecliptic). It’s actually off by about 5^o. In fact, only twice per month does the Moon pass through the ecliptic.

The lunar cycle is approximately 28 days. To be exact, it takes on average 29.53 days (29 days, 12 hours, 44 minutes) between two full moons. The average calendar month is 1/12 of a year, which is 30.44 days. Since the Moon’s phases repeat every 29.53 days, they don’t quite match up. That’s why on Moon phase calendars, you’ll see a skipped day to account for the mismatch.

A second full Moon in the same month is called a blue Moon. It’s also a blue Moon if it’s the third full Moon out of four in a three-month season, which happens once every two or three years.

The Moon isn’t the only object that has phases. Mercury and Venus undergo phases because they are closer to the Sun than the Earth. If we lived on Mars, then the Earth would also have phases.

Exercises

Does the sun always light up half the Moon?
How many phases does the Moon have?
What is it called when the Moon appears to grow?
What is it called when you see more light than dark on the Moon?
How long does it take for a complete lunar cycle?

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Measure your Hair Width with a Laser

Sunday April 21, 2013

Do you have thick or thin hair? Let’s find out using a laser to measure the width of your hair and a little knowledge about diffraction properties of light. (Since were using lasers, make sure you’re not pointing a laser at anyone, any animal, or at a reflective surface.)

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Light is also called “electromagnetic radiation”, and it can move through space as a wave, which makes it possible for light to interact in surprising ways through interference and diffraction. This is especially amazing to watch when we use a concentrated beam of light, like a laser.

If we shine a flashlight on the wall, you’ll see the flashlight doesn’t light up the wall evenly. In fact, you’ll probably see lots of light with a scattering of dark spots, showing some parts of the wall more illuminated than the rest. What happens if you shine a laser on the wall? You’ll see a single dot on the wall.

In this experiment, we used a laser to discover how interference and diffraction work. We can use diffraction to accurately measure very small objects, like the spacing between tracks on a CD, the size of bacteria, and also the thickness of human hair.

Here’s what you need:

a strand of hair
laser pointer
tape
calculator
ruler
paper
clothespin

WARNING! The beam of laser pointers is so concentrated that it can cause real damage to your retina if you look into the beam either directly or by reflection from a shiny object. Do NOT shine them at others or yourself.

Download Student Worksheet & Exercises

Tape the hair across the open end of the laser pointer (the side where the beam emits from)
Measure 1 meter (3.28 feet) from the wall and put your laser right at the 1 meter mark.
Clip the clothespin onto the laser so that it keeps the laser on.
Where the mark shows up on the wall, tape a sheet of paper.
Mark on the sheet of paper the distance between the first two black lines on either side of the center of the beam.
Use your ruler to measure (in centimeters) to measure the distance between the two marks you made on the paper. Convert your number from centimeters to meters (For me, 8 cm = 0.08 meters.)
Read the wavelength from your laser and write it down. It will be in “nm” for nanometers. My laser was 650 nm, which means 0.000 000 650 meters.
Calculate the hair width by multiplying the laser wavelength by the distance to the wall (1 meter), and divide that number by the distance between the dark lines. Multiply your answer by 2 to get your final answer. Here’s the equation:

Hair width = [(Laser Wavelength) x (Distance to Wall)] / [ (Distance between dark lines) x 0.5 ]

In the video:

wavelength was 650 nm = 0.000 000 650 meters
distance from the wall was 1 meter
the distance between the dark lines was 8 cm = 0.08 m

Using a calculator, this gives a hair width of 0.000 0162 5meters, or 16.25 micrometers (or 0.000 629 921 26 inches). Now you try!

What’s Going On?

The image here shows how two different waves of light interact with each other. When a single light wave hits a wall, it shows up as a bright spot (you wouldn’t see a “wave”, because we’re talking about light).

When both waves hit the wall, if they are “in phase”, they add together (called constructive interference), and you see an even brighter spot on the wall.

If the waves are “out of phase”, then they subtract from each other (called “destructive interference”) and you’d see a dark spot. In advanced labs, like in college, you’ll learn how to create a phase shift between two waves by adding extra travel length to one of the waves along its path.

So why are there dark lines along the light line when you shine your laser on the hair in this experiment? It has to do with something called “interference”.

One kind of interference happens when light goes through a small and narrow opening, called a slit. When light travels through a single slit, it can interfere with itself. This is called diffraction.

When light travels through one of two slits, it can interfere with light traveling through the other slit, a lot like how water ripples can interfere with each other as they travel over the surface of water.

If you’re wondering where the slit is in this experiment, you’re right! There’s no narrow opening that light it traveling through. in fact, light appears to be traveling around something, doesn’t it? Light from the laser must travel around the hair to get to the wall. The way that light does this has to do with Babinet’s Principle, which relates the opposite of a slit (a small object the size of a slit) to the slit itself.

It turns out amazingly enough that when light hits a small solid object, like a piece of hair, it creates the same interference pattern as if the hair were replaced with a hole of the same size. This idea is called Babinet’s Principle.

By measuring the diffraction pattern on the wall, we can measure the width of a small object that the light had to travel around by measuring the dark lanes in the spot on the wall. In our lab, the small object is a piece of your hair!

Questions to Ask:

What would happen to the diffraction pattern if the hair width was smaller?
Using this experiment, how can you tell if the hair is round or oval?
If we redid these experiments with a different color laser instead of red, what changes would you have needed to make?
How can you modify this experiment to measure the width of a track on a CD? Does the track width change as a function of location on the CD? If so, is it larger or smaller near the outside?

Exercises

Which light source gave the most interesting results?
What happens when you aim a laser beam through the diffraction grating?
How is a CD different and the same as a diffraction grating?
Why does the feather work?

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Flying Over the Earth at Night

Friday August 24, 2012

Many wonders are visible when flying over the Earth at night, especially if you are an astronaut on the International Space Station (ISS)! Passing below are white clouds, orange city lights, lightning flashes in thunderstorms, and dark blue seas. On the horizon is the golden haze of Earth’s thin atmosphere, frequently decorated by dancing auroras as the video progresses. The green parts of auroras typically remain below the space station, but the station flies right through the red and purple auroral peaks. You’ll also see solar panels of the ISS around the frame edges. The wave of approaching brightness at the end of each sequence is just the dawn of the sunlit half of Earth, a dawn that occurs every 90 minutes, as the ISS travels at 5 miles per second to keep from crashing into the earth.

Video Credit: Gateway to Astronaut Photography, NASA

Earthquakes!

Saturday January 28, 2012

When two blocks of the Earth slip past each other suddenly, that’s what we call an earthquake! From a physics point of view, earthquakes are a release of the elastic potential energy that builds up. Most energy is released as heat, not as shaking, during an earthquake. 90% of all earthquakes happen along the Ring of Fire, which is the active zone that surrounds the Pacific Ocean.

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The Earth has four main layers: the hard skin on the surface is the crust which extends only 30 miles; the hot magma section is a soupy mass of rock that extends approximately 1800 miles; and the core which is made out of two parts: the hot liquid metal outer core surrounds the solid nickel -iron inner core.

The plates on the crust float on magma, which is a lot like the consistency tar. The crust has seven main tectonic plates that slide around and can either slide apart from each other (called a normal fault that is usually found on the sea floor), collide into each other (called a thrust fault), or move in opposite directions (strike-slip fault) at different speeds. Where the plates are sliding apart on the sea floor, the temperature of the water can rise over 1200^oF. Scientists measure the speeds of the plates moving from 1 to 10 inches per year.

There are three different waves that travel through the planet when an earthquake happens. The first waves are the compression-type “P-waves” (primary waves), which travel through the entire planet, including liquid water and solid rock. Most people don’t notice the P-waves, but they do notice the secondary “S-waves”, which follow 60-90 seconds after the P-waves. Following the S-waves are the surface waves, which are like when you wave a bed sheet up and down.

Earthquakes are detected and measured by many different types of instruments, like strain gauges, creep meters, tilt sensors, seismometers, x-ray imagery, and more. These detectors aren’t perfect, though. Earthquake detectors not only discover earthquakes but also glacier movement, nuclear explosions, meteor impacts, and volcano eruptions!

After you watch the video, click the link to do your seismology calculations to figure out both the epicenter and the magnitude of four different earthquakes:

Japan Earthquake 1995 (map answer)
Los Prieta California Earthquake 1989 (map answer)
Mexico Earthquake 1978 (map answer)
Northridge California Earthquake 1994 (map answer)

If you’d like to measure the Earth’s Magnetic Pulse, you can do that here.

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PTC Testing

Friday November 18, 2011

We have done some extensive experiments on taste buds: how they are categorized, what tastes they recognize, and we have even mapped their location on your tongue. But we haven’t yet mentioned this fact: not all people can taste the same flavors!

So today we will check to see if you have a dominant or recessive gene for a distinct genetic characteristic. We’ll do this by testing your reaction to the taste of a chemical called phenylthiocarbamide (or PTC, for short). The interesting thing about PTC is that some people can taste it – and generally have a very adverse reaction. However, some people can’t taste it at all.

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Here’s what you need

1 vial of PTC paper
family members

Download Student Worksheet & Exercises

Here’s what you do

Put the PTC paper in your mouth. If you have the dominant gene, it will usually taste pretty bitter. It might also be sour or even a little sweet. If it tastes like a piece of paper, you have a recessive gene.
After testing your paper, be sure to note whether you are a taster or non-taster.
Now test at least five more people in your family and note their reactions as tasters or non-tasters. Also note their relationship to you.
If you have enough PTC paper, make a genetic tree of your responses. Put Mom and Dad at the center and list you and your siblings branching out beneath them. Then list both sets of grandparents above each of your parents. Circle the names of family members who test positive and leave the negative testers uncircled.

What’s going on?

The gene that determines whether or not you can taste PTC is a part of your DNA (deoxyribonucleic acid). It is the genetic blueprint that you were born with and it determines everything about you: from hair color to the size of your feet. But DNA also plays an important role in how your five senses function. Colorblindness is a genetic deficiency in which a person cannot see colors has a difficult time with distinguishing them. It can range in severity. Some people who are colorblind can’t tell the difference between colors like red and green, but some see no colors at all. Everything looks like a black and white movie to them. Just like colorblindness, our taste sensitivity can vary. Maybe this explains why some people like liver and brussel sprouts and others can’t stand them!

So to relate this to our test, the ability to taste PTC comes from a gene. We know that if both of your parents can taste it, there is a high likelihood that you will be able to taste it, too. About 70%, or 7 out of 10, people can taste it. But what does it mean? In truth, not a lot. It doesn’t mean you have a highly developed palate or a better sense of taste. It just means you are lucky enough to have inherited a gene that allows you to taste a disgusting, bitter chemical on a piece of paper. Congratulations!

Exercises

What are the tiny hair-like organelles that send taste messages to your brain called?
What are the bumps on your tongue called?
What kind of trait does this experiment test?

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Stethoscope

Friday November 18, 2011

Stethoscopes are instruments used to amplify sounds like your heartbeat. Your doctor is trained to use a stethoscope not only to count the beats, but he or she can also hear things like your blood entering and exiting the heart
and its valves opening and closing. Pretty cool!

Today you will make and test a homemade stethoscope. Even though it will be pretty simple, you should still be able to hear your heart beating and your heart pumping. You can also use it to listen to your lungs, just like your doctor does.

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Here’s what you need

3 12-inch lengths of rubber hose
1 “T” connector
1 funnel

Download Student Worksheet & Exercises

Here’s what you do

Take two pieces of hose and work them onto the top ends of the “T” connector. Put the remaining piece of hose onto the bottom of the “T.” The tool you have made should look like a simple stethoscope, but there are no super cold metal end pieces to worry about with yours.
Put the funnel into the bottom hose – the one hanging from the bottom of the “T” connector. You know have a functioning stethoscope. One word of warning: NEVER YELL INTO THE FUNNEL WHILE THE STETHOSCOPE IS ATTACHED TO SOMEONE’S EARS. THIS COULD DAMAGE EAR DRUMS!
Gently insert the side tubes into your ears. Put the funnel on your chest, just to the left of your breastbone. Listen for your heartbeat. If you are in a sufficiently quiet room you may even be able to hear the opening and closing of your heart’s valves.
After you’ve found your hear, try moving the stethoscope to various areas of your chest and listen for different sounds made by your heart. Ask if you can listen to a friend or family member’s heart. Are the sounds made by another heart the same or different?
Now listen to your lungs, placing the end of the stethoscope just above and to the left of the bottom of your ribcage (Point A), to the right of the bottom of your ribcage (Point B), and just below where your ribs start (point C). Also listen in the middle of your back to the left (point D) and right of your spine (point E). In each spot, take a deep breath and listen for the sound of air entering and exiting the lungs.
For your data records, record how many times your heart beats in a minute while you are quiet and sitting.
Next, do 100 jumping jacks. Sit down immediately and check your heart. Record the number of beats per minute for jumping jacks in your data.
Finally, go outside and run for 3 minutes, non-stop. Then sit and immediately check your heart rate one more time. Record the beats per minute for running in your experiment data.

What’s going on?

Exercise creates a demand for oxygen in your muscles, which is received from work done by your heart and lungs. They get a message from your brain and start to work harder. You can see the proof of their hard work in your recorded data.

Exercises

Approximately how big is your heart?
Which body system is the heart a part of?
What are some of this system’s jobs?
How many chambers does your heart have and what are they called?
How did the heart rate change when you exercised?

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What’s Your Lung Capacity?

Friday November 18, 2011

Today you will make a calibrated, or marked, container that you will use to measure your lung capacity. You will fill the calibrated container with water, slide a hose into it, take a really deep breath, and blow in the hose. As the air in your lungs enters the container, it will push out the water inside. Just blow as long and as much as you can, then when you flip the bottle over you will be able to read the amount of water you have displaced. If you will subtract the water displaced from the total amount of water in the bottle, the result is your lung capacity.

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Here’s what you need

- 1 2-liter soda bottle
- 1 black marker, permanent
- 1 12” length of rubber hose
- 1 large plastic bowl
- 1 cup measure

Download Student Worksheet & Exercises

Here’s what you do

Fill the 1 cup measure with water. Pour this into the 2-liter bottle and mark the water level with a line using the black, permanent marker. Also, write 1 cup next to the line. Keep adding water, one cup at a time, marking each new 1 cup increment until you have filled the bottle with water.
Now flip the newly-filled bottle of water over 1 cup measure until the cup is about 1/3 full. Put one end of the rubber hose in the top of the bottle (which should be now under water).
Take a really deep breath – as deep as you can – and blow your breath out into the tube. Continue to blow until you can’t push any more air into the bottle. As air goes in the bottle, it pushes an amount of water equal to its volume out and into the bowl.
Put the lid on the bottle and turn it over before lifting it out of the water. How much water is left in the bottle? Subtract this amount from 8.5 cups. This should be your lung capacity.
Record your lung capacity in your data records as, “My lung capacity is ____________ cups.” You can convert this number to milliliters by multiplying by 0.24. For example, 19 cups would equal 4.5 liters.

What’s going on?

A person who is 70 years old has breathed about 600,000,000 times in their life. But they have also breathed a lot of air – about 13,000,000 cubic feet. This is enough air to fill 52 blimps!

A man’s lungs have a greater capacity than a woman’s – it’s about 6 liters for a man and 4.2 liters for a woman. And since a grown-up has a greater lung capacity than a kid, it makes sense that a 10-year old might breathe 20 times per minute when a grown-up might breathe only 12 times in a minute.

Exercises

Which body system are your lungs a part of?
What are some other parts in this system?
Explain this system’s major function.

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Making Copper

Friday November 18, 2011

In this lab, we’re going to investigate the wonders of electrochemistry. Electrochemistry became a new branch of chemistry in 1832, founded by Michael Faraday. Michael Faraday is considered the “father of electrochemistry”. The knowledge gained from his work has filtered down to this lab. YOU will be like Michael Faraday. I imagined he would have been overjoyed to do this lab and see the results. You are soooo lucky to be able to take an active part in this experiment. Here’s what you’re going to do…

You will be “creating” metallic copper from a solution of copper sulfate and water, and depositing it on a negative electrode. Copper is one of our more interesting elements. Copper is a metal, and element 29 on your periodic table. It conducts heat and electricity very well.

Many things around you are made of copper. Copper wire is used in electrical wiring. It has been used for centuries in the form of pipes to distribute water and other fluids in homes and in industry. The Statue of Liberty is a wonderful example of how beautiful 180,000 pounds of copper can be. Yes, it is made of copper, and no, it doesn’t look like a penny…..on the surface. The green color is copper oxide, which forms on the surface of copper exposed to air and water. The oxide is formed on the surface and does not attack the bulk of the copper. You could say that copper oxide protects the copper.

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Our bodies use copper to our advantage, but in a proper form that is not toxic. Too much copper will make you sick and could kill you. Remember…don’t eat your chemistry set!

Materials:

Carbon rod (MSDS)
Copper sulfate (CuSo₄) (MSDS)
Aluminum foil
9V battery with clip
2 wires
Disposable cup
Water

You are going to make a saturated solution of copper sulfate (CuSO₄) in water. Pour a measuring spoon of granulated copper sulfate in the measuring cup of water. Stir well. Continue adding a spoonful and stirring until no more crystals will go into solution. The solution is saturated when no more crystals will dissolve and there are undissolved crystals at the bottom of the container.

C1000: Experiment

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

CuSO₄ + H₂O (Copper sulfate is added to water)

CuSO₄ + H₂O –> Cu²⁺ + SO₄^2-(Copper sulfate plus water yields positively charged carbon ion and negatively charged sulfate ion)

When mixed with water, copper sulfate dissociates into copper and sulfate ions. Notice that the ions, now separated, take on negative and positive charges.

Next, 9V of electricity is passed through the solution with an electrode of carbon and an electrode of aluminum foil inserted into the solution. As electricity flows from one electrode to another, the copper ions, being positively charged, are attracted to the negative electrode. You can confirm this in two ways. One, if litmus paper, held close to an electrode, turns blue, that is the negative electrode. The other way is to just follow the negative lead from the battery to the negative electrode.

As the process moves along, the negative electrode gains copper ions. Evidence of this is seen on the surface of the electrode.

Here’s the breakdown of the entire process:

When the copper sulfate (CuSO4) mixed with water (H2O), the copper sulfate dissociated:

CuSO₄ –> Cu²⁺ + SO₄^2-

When power is added to the solution, the copper ions move toward the negative cathode (carbon rod) and take electrons from it, forming solid copper right on the electrode:

Cu²⁺+ 2e^– –> Cu_(s)

On the positive anode (the aluminum foil), you’ll see bubbles instead of a solid forming. The anode attracted electrons from the water molecule to form oxygen bubbles:

6H₂O –> O₂ + 4H₃O⁺ + 4e^–

Let’s put these two reactions together to get the overall reaction of:

2Cu²⁺ + 6H₂O –> 2Cu + O₂ + 4H₃O⁺

Note the difference between galvanic cells and electrolytic cells: galvanic use spontaneous chemical reactions (like in a car battery) to generate electricity, and electrolytic cells use electricity to make the chemical reaction to occur and move electrons to move in a way they would go on their own (like in this experiment).

Clean up: Clean everything thoroughly after you are finished with the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. Rinse three times, wash with soap, rinse three times.

Wipe off the carbon rod to remove the copper. The aluminum goes in the trash, but the solution and solids at the bottom cannot. The liquid contains copper, a toxic heavy metal that needs proper disposal and safety precautions. Another chemical reaction needs to be performed to remove the heavy metal from the copper sulfate. Add a thumb sized piece of steel wool to the solution. The chemical reaction will pull out the copper out of the solution. The liquid can be washed down the drain. The solids cannot be washed down the drain, but they can be put in the trash. Use a little water to rinse the container free of the solids.

Place all chemicals, cleaned tools, and glassware in their respective storage places.

Dispose of all solid waste in the garbage. Liquids can be washed down the drain with running water. Let the water run awhile to ensure that they have been diluted and sent downstream.

Going Further

Here is a link to information about making your own geode (crystal lined rock) of copper sulfate crystals:

http://chemistry.about.com/od/growingcrystals/ht/geode.htm

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Working Lung Model

Friday November 18, 2011

Food and air both enter your body through your mouth, diverging when they reach the esophagus and trachea. Food goes to the gastrointestinal tract through your esophagus and air travels to your lungs via the trachea, or windpipe.

You will be making a model of how your lungs work in this lab. It will include the trachea, lungs, and the diaphragm, which expands and contracts as it fills and empties your lungs.

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Here’s what you need

1. 1 2-liter soda bottle, emptied and cleaned
2. 1 pair of scissors
3. 1”Y” valve hose connector
4. 3 round, 9-inch balloons
5. 1 #3 one-hole stopper
6. 1 length of hose, 8-inch
7. 2 rubber bands
8. 1 jar of petroleum jelly

Here’s what you do

Cut off the bottom of the 2-liter bottle. Ask an adult for help.
Take the “Y” valve and secure the two balloons to the top branches with the rubber bands.
Put a tiny bit of petroleum jelly on the end of the hose to make it easier to insert into the #3 stopper. Pull 6 inches of hose through the stopper and then thread the hose through the bottle’s neck. Insert the stopper into the top of the bottle.
Put the end of the hose (that is now inside the bottle) into the base of the “Y” valve (which now has balloons on its other branches). Pull the hose through the stopper a bit. Also, pull the lungs up toward the top of the bottle.
Tie a knot in the third, unused balloon. Cut it in half and stretch the part with the knot over the open bottom of the soda bottle. Make sure the bottom balloon is as tight as it can be.
Grab the bottle with one hand, the knot at the bottom of the balloon with the other. Carefully pull the knot on the balloon down. What happens to the balloons in the bottle? Now let go of the knot and observe how this affects the balloons. Note your observations in the experiment’s data.
Sketch your model and label its trachea, lungs, and diaphragm.

What’s going on?

By placing a stopper in the top of the bottle and putting the stretched rubber balloon on the bottom, you have created an enclosed system. The tube at the top of the bottle is the only way for air to enter or exit the model’s lungs. Pulling down on the balloon’s knot reduced the air pressure inside the lungs. As compensation, air was pushed down into the tube to equalize the pressure. This caused the balloon lungs to expand. When you released the knot, the air pressure forced the air out of the balloons.

If you need more help with identification, the tube acts as the trachea, the balloons are the lungs, and the balloon with the knot at the bottom is the diaphragm.

Did you know that an average person breathes about 24,000 times each day? If you live to be 70 years old, that means about 600,000,000 breaths. Make them count!

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Ammonia Experiments

Friday November 18, 2011

Ammonia has been used by doctors, farmers, chemists, alchemists, weightlifters, and our families since Roman times. Doctors revive unconscious patients, farmers use it in fertilizer, alchemists tried to use it to make gold, weightlifters sniff it into their lungs to invigorate their respiratory system and clear their heads prior to lifting tremendous loads. At home, ammonia is used to clean up the ketchup you spilled on the floor and never cleaned up.

The ammonia molecule (NH₃) is a colorless gas with a strong odor – it’s the smell of freshly cleaned floors and windows. Mom is not cleaning with straight ammonia (it’s gas at room temperature because it boils at -28^oF, so the stuff she cleans with is actually ammonium hydroxide, a solution of ammonia and water). Ammonia is found when plants and animals decompose, and it’s also in rainwater, volcanoes, your kidneys (to neutralize excess acid), in the ocean, some fertilizers, in Jupiter’s lower cloud decks, and trace amounts are found in our own atmosphere (it’s lighter than air).

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Ammonia is a strong base – it combines with acids to form salts:

NH₃ + HCl –> NH₄Cl

But ammonia also can act as a weak acid. Remember, an acid is a proton donor, as in this reaction with lithium, where the ammonia molecule donated one hydrogen atom:

2 Li + 2 NH₃ –> 2 LiNH₂ + H₂

In this experiment, we make a stink and then we see something that will make us go ooooooh…and aaaaw. How fun is that? But you need to follow the instructions carefully and perform your experiment safely. Promise?

Ammonia will be generated by the combination of ammonium chloride and sodium carbonate. The amount of ammonia generated in this experiment is not a large amount. However, you really should experience this particular stink.

Materials:

3 test tubes and rack
sodium carbonate (MSDS)
ammonium chloride (MSDS)
copper sulfate (MSDS)
sodium hydrogen sulfate (NaHSO4) (MSDS) Sodium hydrogen sulfate is very toxic. Respect it, handle it carefully and responsibly. Do not take it for granted.
water
test tube stopper
measuring spoon
gloves, goggles

A chemical reaction is going to occur when the ammonium chloride, sodium chloride, and another chemical reaction is going to occur when the copper sulfate is added. These compounds are the reactants in our chemical reaction, and the blue liquid, CuCl (copper chloride), at the end of the experiment, will be our product. This experiment displays two types of reactions, a decomposition reaction when we combine ammonium chloride and sodium chloride, and a double replacement reaction when we add copper sulfate to the mixture.

C1000: Experiments

Download Student Worksheet & Exercises

When we combine ammonium chloride and sodium carbonate, ammonia will be produced. We will add copper sulfate to that mixture, producing two chemical compounds with totally different properties from those exhibited by the original chemicals.

Two chemical reactions will occur in this experiment:

(1) When you add ammonium chloride and sodium chloride to the water, a decomposition reaction will occur that produces ammonia gas, carbon dioxide gas, and sodium chloride dissolved in water. It is identified as a decomposition reaction because the reactants breakdown into elements or simpler compounds.

NaHCO₃ + 2NH₄Cl –> NH₃ + CO₂ + NaCl + 2H₂O

sodium carbonate + ammonium chloride –> ammonia + carbon dioxide + sodium chloride + water

(2) The next reaction takes place when copper sulfate is added to the sodium chloride and water. The products of this reaction are sodium sulfate and copper chloride (the blue color). This reaction is identified as a double replacement reaction due to the fact that the two reactants break apart and recombine, the reactants trading parts, recombining to form two other different compounds with properties completely different than those of the reactants.

NaCl + CuSO₄ —> NaSO₄ + CuCl

sodium chloride + copper sulfate –> sodium sulfate + copper chloride

Big suggestion here: All chemical vapors are best experienced by “wafting”, a procedure that brings the vapor to you, instead of sticking your nose in the test tube, bringing you to the vapors. Please get in the habit of smelling properly. If ammonia vapors can bring unconscious people back to consciousness, you should probably make sure you are sniffing safely.

Reminder: Always wash your hands or gloves, and your chemistry tools, when switching from one chemical to another to avoid contamination that could affect the experiment adversely.

Store: Put all chemicals away in their proper places to keep them organized and ready to be used again. All tools should be put away as well, but make sure hat they have been cleaned and dried before storing them. A rule of thumb in chemistry is always wash something three times.

Disposal: Pour liquids down the drain using plenty of water. Throw solid waste into the outside garbage to prevent filling the house with bad smells.

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Testing Spit Samples

Friday November 18, 2011

Digestion starts in your mouth as soon as you start to chew. Your saliva is full of enzymes. They are a kind of chemical key that unlock chains of protein, fat, and starch molecules. Enzymes break these chains down into smaller molecules like sugars and amino acids.

In this experiment, we will examine how the enzymes in your mouth help to break down the starch in a cracker. You will test the cracker to confirm starch content, then put it in your mouth and chew it for a long time in order to really let the enzymes do their job. Finally you will test the cracker for starch content and see what has happened as a result of your chewing.

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Here’s what you need

1 package of soda crackers
1 5” pie tin
1 craft stick
1 0.5 oz bottle of iodine
1 pre-form tube
1 1 mL plastic pipette
water

Download Student Worksheet & Exercises

Here’s what you do

Take a cracker from the package and put it in the pie tin. Use your thumb to mash it up, making the pieces as small as possible. Add a small amount of water with the pipette. Mix everything up with the craft stick to make a mash of cracker.
Now fill the pipette with iodine. When iodine comes in contact with starch, it changes in color from reddish-brown to a dark blueish-black. Take the pipette and squeeze a few drops onto the cracker mash in various spots. Record what you see in your experiment data.
Take another cracker and chew it up for about 2 minutes. Do you notice any flavor changes as you are chewing? If so, note this. Be particularly aware of any sweet flavors.
Spit the mash into the pre-form tube once you have chewed for 2 minutes. Use the pipette of iodine to add a few drops of iodine to the chewed mash. Note any change in color. If there is no starch, the iodine will stay reddish-brown in color. If starch is present, you will see the color change to a very dark blue-black as it did in step 2. Record what you see in your data.

What’s going on?

This lab gives you a good idea of what happens in digestion, which starts as soon as food enters your mouth. Actually, the process can start even before this as your body prepares for food. Have you ever had a wonderful smell make your mouth water? This is your body’s way of getting ready to get to work digesting that delicious food.

Once you take a bite and the enzymes start to do their job of breaking large, more complex molecules into smaller particles. In this experiment, starch got broken down into simple sugars that your body could easily move around and use as fuel.

There are three sets of saliva-secreting glands in your mouth. They include a gland in the back of your throat called the parotoid gland, one in your lower jaw called the submandibular gland, and the sublingual gland which is under your tongue. The three work together to secrete up to 2 liters of saliva each day.

Exercises

What is the first step in the digestive process?
How does saliva help to digest food?
Name one or more of the main salivary glands and where they are located.

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Energy from Sugar

Friday November 18, 2011

This experiment is for advanced students.

Purple and white colors, making the whitewash that Tom Sawyer used, and produce an exothermic chemical reaction…..does it get any better?

Limewater is one of the compounds we work with in this experiment. Limewater was used in the old days of America. We’re talking about the 80’s…..the 1880’s.

Traveling medicine shows sold what was called “patent medicines”. These usually had no medicinal properties at all. The man in charge, the salesman of the operation, was called a “huckster”. He would have the one of the people gathered around to listen to him blow into limewater. Their exhaled breath contains carbon dioxide, and the lime water turned cloudy, just like in our experiment.

The man would hold up the glass with the cloudy limewater in it and pour in some of his fantastic remedy. As long as the “medicine” was acidic, it would turn the cloudy limewater clear. This was proof that the remedy would cure whatever ailed the person.

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Today, lime water is used in the traditional making of corn tortillas, tamales, and corn chips. People who have marine (saltwater) aquariums use lime water to assist in maintaining a healthy tank. Lime water is also used in the hide tanning process to remove hair. Parchment paper is made possible by the use of lime water as well. Here’s what you’ll need for your experiment with limewater:

Materials:

Granulated white sugar (MSDS)
Distilled water
Test tube rack
2 test tubes
On-hole rubber stopper
Measuring spoon
90⁰ bend glass tubing
Test tube clamp
Potassium permanganate (KMnO₄) (MSDS)
Sodium hydrogen sulfate (NaHSO₄ ) (MSDS) Sodium hydrogen sulfate is very toxic. Respect it, handle it carefully and responsibly. Do not take it for granted.
Measuring syringe
Calcium hydroxide, Ca(OH)₂ (MSDS) to add to H₂0 to make limewater (MSDS)

Keep the potassium permanganate solution from entering the glass tube and being transported into the limewater.

Saturated calcium hydroxide solution has been historically called lime water Ca(OH)₂ . That is what we will be bubbling our carbon dioxide into. It looks like water, but isn’t. Limewater smells like dirt and has an alkaline taste. (Don’t taste to find out. Not a safe laboratory practice.)

Saturated calcium hydroxide solution has been used as paint since the early years of the settlement of America. Ever hear of Tom Sawyer and the whitewashed fence? Whitewash is another name for limewater. We’re going to be using some pretty nasty chemicals, but you already follow all the safety precautions. Just remember to remember, and be careful.

The solution in one of your test tubes is going t undergo a chemical reaction to produce carbon dioxide. Another solution will be the indicator that CO₂ has been produced.

C3000: Experiment

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

When carbon dioxide is produced and bubbled into the lime water, a chemical reaction takes place.

Ca(OH)₂ + CO₂ –> CaCO₃ + H₂O

Calcium hydroxide (lime water) and carbon dioxide yields calcium carbonate and water. A milky precipitate forms that is calcium carbonate (CaCO₃).

Cleanup: Clean everything thoroughly after you are finished with the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. After washing, chemists rinse out all visible soap and then rinse three times more.

Storage: Place all chemicals, cleaned tools, and glassware in their respective storage places.

Disposal: Dispose of all solid waste in the garbage. Liquids can be washed down the drain with running water. Let the water run awhile to ensure that they have been diluted and sent downstream.

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Getting Air from Water

Friday November 18, 2011

This experiment is for advanced students. This is a repeat of the experiment: Can Fish Drown? but now we’re going to do this experiment again with your new chemistry glassware.

The aquarium looked normal in every way, except for the fish. They were breathing very fast and sinking head first to the bottom of the tank. They would sink a few inches, then jerk into proper movement again.

The student had to figure out what was wrong. He had set up the aquarium as an ongoing science project, and it was his responsibility to maintain the fish tank. His grade depended on it.

He went to his mom for help. She looked over the setup. “Have you tested the water?”

A quizzical look on his face, the boy said, “Everything is normal nitrates, nitrites, hardness, alkalinity, and pH. The pH was a little acidic, but not outside the proper range.”

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His mother said to him, “Show me how you would look if you were gasping for air and look in the mirror while you do it.”

He did, and he remarked, “I look like my fish.” I swear a light bulb actually appeared over his head and lit all up. He said, “They need air!” His mom was standing near the aquarium holding an air pump, vinyl tubing, and an air stone.

“Looking for this?” His mom said. He and his mom set up the air pump and soon his fish were jumping in the air and kissing him on the cheek. Well, maybe not that last part, but you get the idea. Water does not contain an inexhaustible amount of oxygen in it. It must be replenished if there is something in the water that is using it up.

The oxygen carrying capacity of water varies with conditions. Rainbow trout are found in cold water streams because the colder the water, the more oxygen it will hold. Rainbow trout need lots of oxygen in their water to survive. Other species of fish are found only in warmer water because they are adapted to a condition of less oxygen in the water. Still other fish can gulp the air from the surface if the water is severely depleted of oxygen. I have seen carp gulping air as they swim around in a pond looking for food on a hot summer day.

In this experiment we will discover that water does contain oxygen. We will subject the water to heat and we will see the oxygen for ourselves.

Materials:

Test tube rack
Test tube
Test tube holder
Rubber stopper
90 degree bent glass tubing
Alcohol burner
Striker

Be careful not to let your water boil. Pressure will build up inside the test tube because only a small amount of pressure at a time can leave via the glass tubing. Pressure will build up and the stopper will fly off or the test tube will rupture. (Glass shrapnel and boiling water will get all over you. Not a pleasant thought.)

Inserting the glass tubing into and through the stopper is the most dangerous part of this lab or any other lab requiring this to be done. Most lab injuries, student or chemist, are due to cuts from broken glass. Proper technique will save you the pain of a deep cut. Lubricate the rubber stopper with glycerol if you have it. (It is a non-reactive laboratory grease that will not contaminate as badly as household or automotive oils and greases.) DO NOT use any other grease or oil. You probably don’t have any glycerol, so your second choice is just plain old water.

So, water on the tubing, gently start the glass tubing into the stopper. Don’t grip the glass with your hands, get a thick wash cloth, small towel, or work gloves and grab the tubing. Gently twist the tubing as you push gently on the tubing. Don’t pull to one side or the other, make your push a straight line. Once the tubing gets going, don’t stop unless you have to. Your second shot may be much more difficult because you have pushed a lot of the water off the tubing.

You are not going to see a chemical change. You are not going to work with chemicals. You are going to see for yourself that there is oxygen in water. That is, of course, what fish use up in the water. Unless it is replenished, fish can’t breath and they suffocate….not drown. The oxygen is replenished in the wild through various means. We can replenish the water with air pumps and water changes.

C3000: Experiment

Heated surfaces will be hot for awhile. Let things rest for a couple of minutes before doing your cleanup.

Your test tube probably has a blackened surface. It should wipe off easily, or will with a little soap, water, and a light touch.

Storage: Place all chemicals, cleaned tools, and glassware in their respective storage places.

Disposal: Dispose of all solid waste in the garbage. Liquids can be washed down the drain with running water. Let the water run awhile to ensure that they have been diluted and sent downstream.

The filter pump in your fish tank ‘aerates’ the water. The simple act of letting water dribble like a waterfall is usually enough to mix air back in. Which is why flowing rivers and streams are popular with fish – all that fresh air getting mixed in must feel good! The constant movement of the river replaces any air lost and the fish stay happy (and breathing). Does it make sense that fish can’t live in stagnant or boiled water?

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Working with Cataylsts

Friday November 18, 2011

This experiment is for advanced students.

Don’t put this in your car….yet. Hydrogen generation, capture, and combustion are big deals right now. The next phase of transportation, and a move away from fossil fuels in not found in electric cars. Electric cars are waiting until hydrogen fuel cell vehicles become practical. It can be done and is being done.

Cars being powered by hydrogen are here, but not on the market yet. Engineers and chemists are always finding new ways to improve the chemical reaction that produces hydrogen and making the vehicles more efficiently use the fuel. Hydrogen fuel is not just easy to make, it is inexpensive, and the “exhaust” is water.

We will generate hydrogen in this lab. We will also see how combustible it is. Just let your imagination wander….just a bit and you will see noiseless cars and trucks zipping along the streets and interstates, carrying people and cargo. The Indianapolis 500 wouldn’t be quite the same, though. “And there they go, roaring, I mean quietly entering turn two…”

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Materials:

Goggles
Gloves
Measuring syringe
Water
Test tube rack
One-hole rubber stopper
Alcohol burner
Lighter
Test tube
Test tube holder
Water bath
Chemistry stand
Rubber tubing
90 degree bend glass tubing
Zn powder (MSDS)
Copper sulfate CuSo₄(MSDS)
Sodium hydrogen sulfate NaHSO₄(MSDS) Sodium hydrogen sulfate is very toxic. Respect it, handle it carefully and responsibly. Do not take it for granted.

We will combine sodium hydrogen sulfate, water, and zinc. As soon as they are all together in our test tube, bubbles will begin forming in the solution. The bubbles will continue coming off, but we can speed up the reaction by adding a little copper sulfate. Now, instead of leisurely coming off, the gas is being given off quickly and we must act quickly ourselves to capture as much of the gas as possible. We can aid the gas movement ourselves by swirling the solution gently.

C3000: Experiment

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

NaHSO₄ + H₂O + Zn + CuSO₄–> H₂ + NaSO₄ + CuHSO₄ + ZnO

Sodium hydrogen sulfate is added to water and dissolved completely. Zinc is added and hydrogen gas is generated by the chemical reaction. Copper sulfate is added as a catalyst to speed up the generation of hydrogen.

Double replacement occurs where the compounds are broken apart and the pieces realign and re-bond with different parts of the original molecules, and zinc oxide is left as a byproduct of the oxidation of the zinc powder. Hydrogen gas is freed in the reaction.

Cleanup: We are going to clean everything thoroughly after we finish the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. After washing, chemists rinse out all visible soap and then rinse three times more.

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids must be neutralized before they can be washed down the drain. Solids are thrown in the outside trash.

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Hydrogen Peroxide

Friday November 18, 2011

This experiment is for advanced students.

In industry, hydrogen peroxide is used in paper making to bleach the pulp before they form it into paper. Biologists, when preparing bones for display, use peroxide to whiten the bones.

At home, 3% peroxide combined with ammonium hydroxide is used to give dark-haired people their desired blonde moment. Peroxide is also used on wounds to clean them and remove dead tissue. Peroxide slows the flow from small blood vessels and oozing in wounds as well.

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Peroxide is a chemical produced in a Bombardier Beetle, and it squirts its irritating load into the face or onto the lips of a predator. Zebra fish produce peroxide after their skin is damaged. This action acts as a signal to produce an abundance of white cells to fight any infection and assist in the healing.

Scientists believe that healing can occur in humans in the same way. Future experiments may prove them right. It is also believed that people who have asthma have elevated levels of peroxide in their lungs, levels much higher than people without asthma.

Hydrogen peroxide can also help an animal that has eaten poison. A small amount of it can be put down the animal’s throat to induce vomiting and clear the poison out of their body as much as possible. Did your dog get too close to a skunk? There is no real “cure” other than a lot of time outside to air out, but peroxide mixed with hand soap is pretty good at removing the stink. Then, how you remove that stink from yourself…..another problem.

Materials:

2 test tubes
Burner
Lighter
Chemistry stand
Test tube holder
Glass jar
Water pan
Water
Rubber tubing
90^o glass tubing
3% Hydrogen peroxide (H₂O₂) (MSDS)

Hydrogen peroxide comes in a dark bottle because sunlight will slowly decompose hydrogen peroxide in the same way that we are doing with the exception that our way is much quicker.

When finished heating hydrogen peroxide, if you leave everything together, water will climb the tubing and attempt to enter the hot test tube. Cold water and hot peroxide are not safely compatible. To avoid this, remove the stopper from the test tube and set it aside while the solution cools.

Wait until all the equipment is cool enough to touch before disassembling for cleaning and storage.

When heating the test tube, be careful. Don’t heat in one place for too long. Move the flame of the burner around periodically to heat the reaction area of the test tube uniformly.

Don’t boil the peroxide too vigorously. If boiling gets too wild, remove the burner form the test tube until it calms down, then move it back to heat again.

At all times, keep the flame and peroxide apart…well apart.

Hydrogen peroxide is going to get broken down, is going to decompose, into the base elements of hydrogen and oxygen.

C3000: Experiment

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

Hydrogen peroxide (H₂O₂) breaks down with heat. A decomposition reaction occurs where hydrogen peroxide breaks down into its component elements, H₂ and O₂

2H₂O₂ –> 2H₂O + O₂

2 molecules of hydrogen peroxide are heated, creating a chemical decomposition reaction, producing 2 molecules of water and 1 molecule of oxygen.

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids can be washed down the drain

Going further: Elephant’s Toothpaste

A really fun experiment with hydrogen peroxide is making Elephant’s toothpaste. It requires an adult helper, and is fun for the kid and the adult.

Materials:

Empty 20 or 24 ounce plastic bottle
3 % hydrogen peroxide
Liquid dish soap
Warm water
Food coloring
One packet or 2 1/2 ounces of yeast
One really big container to contain the big mess – laundry tub, bathtub, etc.

This video below is a demonstration of the Elephant Toothpaste experiment using much nastier chemicals than the ones I’ve mentioned above… the hot gas generated is actually oxygen. Enjoy!

Procedure:

Dissolve the yeast in a little warm water and stir well. Use just enough water to make a pourable liquid. Let it sit for about 5 minutes while you prepare the rest of the experiment.
Pour 1/2 cup of hydrogen peroxide, 1/4 cup of dish soap and a little bit of food coloring in the bottle. Swirl to mix and put the bottle in the middle of your large pot, container or sink.
Pour the yeast solution into the bottle. A funnel can help, but be prepared to pour fairly quickly and remove it again because the reaction will start as soon as you start pouring.
Stand back and watch the fun!

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Generating Oxygen

Friday November 18, 2011

This experiment is for advanced students.

This time we’re going to use a lot of equipment… really break out all the chemistry stuff. We’ll need all this stuff to generate oxygen with potassium permanganate (KMNO₄). We will work with this toxic chemical and we will be careful…won’t we?

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Oxygen is pretty important… it’s only the single most important thing that mammals need. Besides breathing, oxygen is important for so much on this world. Oxygen is used in welding, rocket fuel, and water treatment. Without oxygen, there is no oxidation and no fire. Simply put, we wouldn’t have rusty bicycles or campfires. Can your believe it?

Potassium permanganate is an important chemical in the film industry. It is used to make props like cloth, ropes, and glass, appear “old”. Some films it has been used in are “Troy”, “Indiana Jones”, and “300”. The KMnO₄ stains any organic material. KMnO₄is also used as an antiseptic, and is used to treat skin ulcers and rashes. It is also used to treat foot fungus…..phew! People living in the country are sometimes plagued with an iron taste or a rotten egg smell in the water from their wells. Potassium permanganate can be used to remove the taste and smell from the water.

Materials:

Chemistry stand
Plastic tub
Water
2 test tubes
Test tube clamp
Potassium permanganate (KMnO₄) (MSDS)
Alcohol burner
Lighter
One-hole rubber stopper
Solid rubber stopper
90⁰ bend glass tube
Measuring spoon
Rubber tubing
Match
Wooden splint

Be careful inserting the glass tubing into the stopper. Wet the short end of the glass tube with water and gently push and twist the glass through the stopper. Wear work gloves and work carefully and slowly. Do not use oil or grease you have laying around the house.

When lighting the oxygen in the test tube, use a wooden splint. Wooden splints can be purchased from craft stores, or make your own by shaving thin strips from a piece of pine wood.

C3000: Experiment

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

2KMnO₄ + O₂ –> K₂MnO₄ + MnO₂ + O₂

Potassium permanganate is heated and produces potassium manganate, manganese dioxide, and oxygen

Oxygen is generated by heating the KMnO₄, and is collected in the test tubes. We will test the contents of the tubes to see if oxygen has been generated. What do you think will happen when a glowing splint is pushed up inside the test tube? Don’t know? Do the experiment and try to figure it out. Remember, in order for there to be flame, you need fuel and oxygen. If that gas was carbon dioxide, what would happen when the glowing splint was placed inside?

Storage: Place all chemicals, cleaned tools, and glassware in their respective storage places.

Disposal: Dispose of all solid waste in the garbage. Liquids can be washed down the drain with running water. Let the water run awhile to ensure that they have been diluted and sent downstream.

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Heart Rate Monitoring

Friday November 18, 2011

When you exercise your body requires more oxygen in order to burn the fuel that has been stored in your muscles. Since oxygen is moved through your body by red blood cells, exercise increases your heart rate so that the blood can be pumped through your body faster. This delivers the needed oxygen to your muscles faster. The harder you exercise, the more oxygen is needed, so your heart and blood pump even faster still.

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Here’s what you need

1 clock with a second hand
1 pencil

Download Student Worksheet & Exercises

Here’s what you do

While sitting quietly, place your first two fingers of one hand onto the wrist of the other hand. Feel for the pulse of your radial artery. Practice taking your pulse in intervals of 6 seconds.
After you have had some practice with the 6 second interval, take your pulse for this amount of time and multiply it by 10. The 6-second rate times 10 is your heart rate per minute. Record each for experiment data.
Now stand up and do 50 jumping jacks. When done, sit down immediately and check your pulse. Again, record the 6-second pulse rate, multiply it by 10 and also record the pulse rate per minute.
Finally, go outside and run around as fast as you can without stopping for 3 minutes. Again, immediately sit and take your pulse. Record the 6-second rate, multiply it by 10 and get your heart rate per minute.

What’s going on?

Exercising means your muscles need more oxygen. They ask your brain to tell your heart and lungs. When your heart gets the message, it starts to beat harder. Your lungs work harder, too. Together, your heart and lungs work as a team to provide the needed oxygen supply to your muscles. You can identify that this process is occurring by your heart rate increase and more rapid breathing rate.

Did you know that your heart is about the size of your fist? It is actually a muscle and it pumps more than a gallon of blood through your body each minute! An average heart rate is 70 beats per minute, but this can vary depending on age and fitness level. Based on 70 bpm, your heart will beat around 100,000 times per day. That’s more than 36 million beats a year!

Exercises

Explain how to take a pulse.
What units do we use to measure pulse?

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Detecting Carbon Dioxide

Friday November 18, 2011

An oxygen and carbon dioxide exchange takes place in your bloodstream. When you breathe air into your lungs it brings in oxygen, which is carried from your lungs by red blood cells in your bloodstream. Cells of your body use the oxygen and carbon dioxide is produced as waste, which is carried by your blood back to your lungs. You exhale and release the C02. You will study this exchange in today’s lab.

You will be using a pH indicator known as bromothymol blue. When you exhale into a baggie, the carbon dioxide will react with water in the bag. This reaction produces carbonic acid, which starts to acidify the water. More breathes in the bag equal more carbon dioxide, which equal a lower (more acidic) pH. You will notice the bromothymol will turn green when the pH of the water is right about 6.8 and it will turn yellow when the pH drops further to 6.0 and lower.

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Here’s what you need

- 1 1 oz. bottle of bromothymol blue
- 1 straw
- 1 resealable baggie
- 1 bottle of ammonia
- 1 pipette
- water

Download Student Worksheet & Exercises

Here’s what you do

Pour about 2 ounces of water into the baggie and add two capfuls of the bromothymol blue into it. Close the baggie well and swish the solution around inside it gently to mix. Note the color of the solution for your data record.
Open the baggie a tiny bit and put the straw inside, but DO NOT drink the solution! It could make you sick. Close the bag tightly around the straw and gently blow into the solution. Again, be careful not to suck on the straw.
Watch the color of the solution closely as you continue to blow into the solution and create bubbles of carbon dioxide gas. The color will change to a sea green color and then eventually it will change to bright yellow. Note each color change in your records.
You can return the solution to blue by slowly adding a base – such as ammonia – to the solution in the bag. Bleach will also work. Please ask an adult to help with this. Add one drop at a time, shaking after each addition to mix the solution. You will be able to observe when the pH starts to change back by the color of the solution. It should turn back to green and then to blue.

What’s going on?

Bromothymol blue will change color in a pH range from 6.0 to 7.6. It is an acid/base indicator. Its basic solution is at a pH of 7.6 or above – this is when it is blue. In acidic conditions, it will turn yellow – this is a pH of 6.0 or below. And when it’s in between the two, it will be the sea green color that you observed in your baggie.

Because carbon dioxide is a little acidic, when we breathe it out into the water and bromothymol blue solution its bubbles start to lower the pH. You saw a small change in pH with the sea green color, but as you continued to exhale and add carbon dioxide, the solution became more and more acidic. This eventually resulted in a pH at or below 6.0 and a bright yellow solution.

In order to exchange oxygen with carbon dioxide in your lungs, they have over 300,000,000 teeny little air sacs calls alveoli. In one minute, you breathe approximately 13 pints of air.

Exercises

What is pH and how it is useful?
What does a yellow color indicate with bromothymol blue?
Is CO₂ acidic or basic?

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Making Sodium Hydroxide

Friday November 18, 2011

This experiment is for advanced students.

Ever use soap? Sodium hydroxide (NaOH) is the main component in lye soap. NaOH is mixed with some type of fat (vegetable, pig, cow, etc). Scent can be added for the ‘pretty’ factor and pumice or sand can be added for the manly “You’re coming off my hands and I’ll take no guff” factor. Lots of people still make their own soap and they enjoy doing it.

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One of the coolest uses for sodium hydroxide is in tissue digestion. By “tissue” we mean meat, bone, sinew…..meaning bodies! People who pick up dead animal (road kills) for the county dump their catch in barrels containing sodium hydroxide. The NaOH eats everything up and then the “sludge” is dumped in the landfill. They used NaOH to make them decompose. So this stuff is nasty and should never be touched with your bare hands!!

Materials:

Erlenmeyer flask
Alcohol burner
Lighter
Heating rod
Sodium carbonate (Na₂CO₃) (MSDS)
Calcium hydroxide (Ca(OH)₂) (MSDS)
Measuring spoon
Water
Tripod stand
Wire screen
Chemistry stand
Test tube holder
Test tube rack
Test tube
Filter paper
Funnel
Stock bottle for NaOH storage (MSDS)

Don’t inhale any fumes from reactions or powder welling out of chemical containers, especially calcium hydroxide dust. We want to test our product to see if it is NaOH. It should turn red litmus blue.

We will perform a bunch of operations in this lab.

Heating our calcium hydroxide / sodium carbonate mixture to create calcium carbonate and sodium hydroxide.
Filter out the calcium carbonate to collect the sodium hydroxide.
Test our sodium hydroxide product for the properties of NaOH.

C3000: Experiments

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

Ca (OH)₂ + Na₂CO₃ –> 2NaOH + CaCO₃

Calcium hydroxide and sodium carbonate are combined in water and heated to produce sodium hydroxide and calcium carbonate

This is a double replacement reaction because the calcium ion and the sodium ion have swapped places

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids must be neutralized with vinegar, if a base, or baking soda, if an acid, before washing them down the drain. Before actually washing them down the drain check again with litmus paper to ensure that they have been neutralized. Solids are thrown in the trash.

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Potassium Permanganate

Friday November 18, 2011

This experiment is for advanced students.

Potassium permanganate (KMnO₄) in water turns an intense, deep, purple. It is important in the film industry for aging props and clothing to make them look much older than they are.

Also, artists use it in bone carving. People who carve antlers and bone use KMnO₄ to darken the surface of the bone to make it look aged. They make the carving, soak it in potassium permanganate, then carve more, and repeat. The end result is a carving that has a light golden brown color. More dipping will darken the carving even more.

Potassium permanganate is going to undergo a chemical change with this activity. In this experiment, we will be able to witness several indicators of chemical change. Color changes, bubbles from gas generation, temperature change, and color disappearance are all indicators of chemical changes.

[am4show have='p9;p52;p91;' guest_error='Guest error message' user_error='User error message' ] Examples of chemical color changes we might be familiar with are autumn leaves changing color and a half eaten apple quickly turning brown.

Physical changes can mimic the indicators of chemical change, so we will need to always think through what we observe and then decide whether it is a physical or chemical change. Physical changes that mimic chemical changes can be color and temperature. The key is that physical changes are changes in state (solid, liquid, gas, sublimation) or changes in the condition of the material. In our pursuit of science knowledge, we will observe many physical and chemical changes. We need to be able to identify them accurately to really understand what is happening in an experiment.

Materials:

3% Hydrogen peroxide (KMnO4) (MSDS)
Test tube rack
2 test tubes
Potassium permanganate (KMnO4) (MSDS)
Sodium hydrogen sulfate (NaHSO4) (MSDS) Sodium hydrogen sulfate is very toxic. Respect it, handle it carefully and responsibly. Do not take it for granted.
Measuring syringe
Water
Measuring spoon
Solid rubber stopper

NOTE: Be very careful when handling the sodium hydrogen sulfate – it’s highly corrosive and dangerous when wet. Handle this chemical only with gloves, and be sure to read over the MSDS before using.

Always cap your chemicals after use and set them aside where they won’t get in the way. Your lab area should always be clear, clean, and uncluttered. Water and a fire extinguisher should be within arm’s reach. Always clean equipment before using any of it on another chemical.

Potassium permanganate is going to undergo a chemical reaction that will turn the deep violet or purple solution clear. It is a very cool experiment and looks like a lot of fun.

C3000: Experiment

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment: KMnO₄ + NaHSO₄ + H₂O₂ = MnSO₄ + O₂ + NaOH + KOH

Potassium permanganate is added to sodium hydroxide, and then hydrogen peroxide is added and quickly capped.

MnSO4 + O2 + NaOH + KOH

The product of the reaction is manganese sulfate, oxygen, sodium hydroxide, and potassium hydroxide. The remaining chemicals are all clear, so the desired result is obtained.

Cleanup: Clean everything thoroughly after you are finished with the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. After washing, chemists rinse out all visible soap and then rinse three times more.

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids can be washed down the drain

Click here for Homework Problem Set #14

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Potassium Hexacynoferrate (Reagant)

Friday November 18, 2011

This experiment is for advanced students.

How do you know if your brother is stealing your candy? Unwrap a wrapped hard candy that he likes a lot. Roll the candy around in the powdered food dye that matches the candy. (Push the powder into the candy so it “disappears”.) Re-wrap the candy. Set the candy in the place where it usually disappears from. Wait ten minutes after the candy disappears. Find your brother. He will be sporting a new color on his hands and mouth. Dye is hard to remove. It will have to be worn every day at school until it fades away as the skin cells slough off. The dye he now wears is in indicator that he has been taking your candy.

[am4show have='p9;p52;' guest_error='Guest error message' user_error='User error message' ] Did you guess that this lab is about indicators? A reagent is chemical compound that creates a reaction in another substance; the product of that chemical reaction is an indicator of the presence, absence, or concentration of another substance.

Your brother’s situation is not a chemical reaction, but a reaction will be observed in his looks and his mood.

We are going to prepare copper sulfate and ammonium iron sulfate solutions and test them to see if our reagent, potassium hexacynoferrate II will cause chemical changes that indicate that copper is present in one, and iron is present in the other.

I’m sure your brother will stay far away from your candy from now on. I know this is obvious, but don't eat anything in this lab or use it to coat candy... that was just an example to illustrate what an indicator is and how to use it.

Materials:

Erlenmeyer flask
Water
Potassium hexacynoferrate II K₄Fe(CN)₆ (MSDS)
Copper sulfate CuSO₄(MSDS)
Measuring spoon
Solid rubber stopper
Test tube rack
3 Test tubes
Measuring syringe
Small labeled container for NaOH
Dropper pipette
Ammonium iron sulfate NH₄Fe(SO₄)₂(MSDS)
Sodium hydroxide NaOH (MSDS)

We need to remember to only make as much Potassium hexacynoferrate II as we need. Label test tubes with contents information clearly visible. Always remember that when the term “reagent” is used in chemistry it is referring to an indicator chemical.

We will put together two solutions with metallic chemicals dissolved in water in each. Let’s pretend we have no idea if they are metallic or not. Many times as a chemist, when analyzing a customer’s of a production chemical, we are looking for metal in a solution as an indicator of something good or something bad. If one of the factory’s systems contains a corrosive liquid flowing through its veins, it would be good to know if some metal somewhere is corroding, being dissolved, by the fluid. Our tests could confirm a problem or set the boss’s mind to rest….and get us a big bonus if we save the day.

C3000: Experiments

Here’s what’s going on in this experiment:
In test tube #1: Copper sulfate solution into which we added Potassium hexacynoferrate II. A color change occurred (brown) and a precipitate fell out of the liquid to rest on the bottom of the test tube. This reaction was an indicator for the presence of metal.

In test tube #2: Ammonium iron sulfate solution into which we added Potassium hexacynoferrate II. A color change occurred (dark blue). This reaction was an indicator for the presence of metal.

Cleanup: We are going to clean everything thoroughly after we finish the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. After washing, chemists rinse out all visible soap and then rinse three times more.

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids, after neutralization, can be washed down the drain. Solids are thrown in the trash.

Click here to go to next lesson on Characteristics and capacity of buffers

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Iodine

Friday November 18, 2011

This experiment is for advanced students.

In gas form, element #59 is deadly. However, when iodine is in liquid form, it helps heal cuts and scrapes. The iodine molecule occurs in pairs, not as a single atom (many halogens do this, and it's called a diatomic molecule). It's hard to find iodine in nature, though it's essential for staying healthy... too little iodine in the body takes a heavy toll on how well the brain operates.

A chunk of iodine is blackish-blue, and will sublimate (go from a solid straight to a gas). Iodine is the heaviest element needed by living things. Iodized salt is sodium chloride fortified with iodine to prevent people from not getting enough iodine in their daily diets.

Iodine is found in seaweed (kelp) and seafood as well as vegetables that are grown in dirt that has high iodine levels. People that live inland and do not eat fish often have lower iodine levels than their coastal, fish-eating neighbors. The trick is not to get too much or too little iodine in your diet, because the symptoms of deficiency and excess levels are quite similar.

Starch (like cornstarch) are used as an indicator for detecting iodine in chemistry experiments. When combined with iodine, starch forms a blue-black color in the solution. We're going to do this and many other activities in this lab, because this experiment is actually several labs rolled into one. First, we have to make iodine, store it, and then we get to use it in several experiments. Are you ready?

[am4show have='p9;p52;p91;' guest_error='Guest error message' user_error='User error message' ] Materials:

Goggles
Gloves
Glass jar
Chemistry stand
Test tubes
Test tube holder
Measuring spoon
Corn starch peanut
Water cup
90 degree bend glass tubing
One-hole rubber stopper
Paper towels
Stain-free work surface
Solid rubber stopper
Denatured alcohol
Dark brown glass storage bottle for iodine
Dropper pipettes
Alcohol burner
Lighter
Measuring syringe
Water
Potassium iodide KI (MSDS)
Potassium permanganate KMnO4 (MSDS)
Sodium hydrogen sulfate NaHSO4 (MSDS) AKA: Sodium Bisulfate Sodium hydrogen sulfate is very toxic. Respect it, handle it carefully and responsibly. Do not take it for granted.

NOTE: Be very careful when handling the sodium hydrogen sulfate – it’s highly corrosive and dangerous when wet. Handle this chemical only with gloves, and be sure to read over the MSDS before using.

Remember that iodine is toxic paper and harmful to the environment. Safely shake test tube to homogenize chemicals using a solid rubber stopper and dispose of in the outside trash.

NOTE: Heat slowly and carefully. You don’t want your test tube in the flame. The end of the glass tubing should not extend into the alcohol. From time to time, touch the end of the glass tubing to the alcohol to rinse iodine from the tube into the alcohol, but the glass tubing shouldn’t reside in the alcohol. Conduct this experiment outdoors or in an extremely well ventilated area inside the house.

Follow cleanup instructions carefully for safety. These are very toxic substances we are working with.

As heating progresses, purple gas will form in the upper test tube. A brown color will begin to form in the alcohol. Heat until purple smoke disappears from the upper test tube.

C3000: Experiments

Here’s what’s going on in this experiment: 2KI + KMnO₄ + NaSO₄ + H₂O--> I₂ + MnO₂ + KOH +KIO₃ + Na₂SO₄

Potassium iodide and potassium permanganate and sodium sulfate and water are heated to produce free iodine gas and magnesium oxide and potassium hydroxide and potassium iodide and sodium sulfate.

All this to produce the iodine we need for the next several experiments.

Cleanup: We are going to clean everything thoroughly after we finish the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. After washing, chemists rinse out all visible soap and then rinse three times more.

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids need to be filtered through a paper towel and washed down the drain with plenty of water. Solids are thrown in the outside trash.

Going Further

*Save all solutions you make in these experiments. You will use them in the other experiments.

Testing Iodine solution

After the drops of iodine are in the test tube with water, observe. Any solid particles in the test tube prove that our iodine is not soluble in water.

Addition with Iodine

Using the solution from the above experiment, adding KI will dissolve all the solids that were observed. Why did the solids disappear? Well, nothing dramatic was seen, but an addition compound was created.

I₂ + KI --> KI I₂

Sodium Thiosulfate

Sodium thiosulfate (Na2S2O3) solution is pipette drop by drop to above solution until it turns clear. The reaction that takes place turns our solution into sodium hypoiodite (NaOI)

Packing Peanut

We fill a glass jar with water and 10 drops of iodine and mix well. The water will be a pale brown. Dissolve a corn starch peanut in water. When we add starch solution to the iodine and water, the water turns clear, then blue. We have just created iodine starch!

Colorless Iodine

Sodium thiosulfate solution from an experiment above. Put a few droppers of this solution into the iodine starch and stir. Colorless! We have a colorless iodine solution….very cool!

Iodine and Heat

To set this one up, dropper one drop of iodine solution into a test tube half-filled with water. Then we regain our bright blue color by adding our starch solution to the iodine water. When we add heat, The solution turns clear! But, we’re not done. The test tube goes into a half full jar of cool water. The solution in the test tube is turning blue. If you keep doing these actions over and over again, you will keep getting the same results. Did you notice something? The reaction is ________. Think, now. (Psst! It's reversible!)

Colorless Iodine Without Heat

In this experiment we use alcohol to achieve a clear solution. We pour some iodine starch solution into some alcohol and the solution turns clear. The alcohol removed the iodine from the solution.

Click here to download Equilibrium Constants and Reaction Mechanisms.

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Hydrogen Bromide

Friday November 18, 2011

WARNING!! THIS EXPERIMENT IS PARTICULARLY DANGEROUS!! (No kidding.) This experiment is for advanced students.

We've created a video that shows you how to safely do this experiment, although if you're nervous about doing this one, just watch the video and skip the actual experiment.

Bromine is a particularly nasty chemical, so be sure to very carefully follow the steps we've outlined in the video. You MUST do this experiment outdoors. We'll be making a tiny amount to show how the chemical reactions involving bromine work.

[am4show have='p9;p52;' guest_error='Guest error message' user_error='User error message' ] Isn’t it interesting how many ways we can use the same techniques and, by just changing a few chemicals, we can learn about so many different chemical reactions? This lab is similar in technique to the Generating Hydrochloric Acid lab. Using the same techniques, we will produce hydrogen bromide.

Hydrogen bromide (HBr) was used as a sedative in the late 1800s and early 1900s. Once they found out how poisonous it really was (after enough people became blind and/or dead), someone had the wonderful idea that maybe we shouldn’t use it anymore. It was also used to control epilepsy until the substitute Phenobarbital came on the scene in 1911. HBr is still used to treat epilepsy in dogs. In cats HBr causes inflammation of the lungs and makes for a very unhappy cat.

Materials:

Alcohol burner
Lighter
Wire screen
Tripod stand
Glass jar
Rubber tubing
900 Glass tubing
One-hole rubber stopper
Chemistry stand
Test tube holder
Test tube
Potassium bromide (KBr) (MSDS)
Sodium hydrogen sulfate (NaHSO₄) (MSDS) Sodium hydrogen sulfate is very toxic. Respect it, handle it carefully and responsibly. Do not take it for granted.
Burette
Water
Sodium carbonate (Na₂CO₃) (MSDS)
Silver nitrate (AgNO₃) (MSDS)

NOTE: Be very careful when handling the sodium hydrogen sulfate – it’s highly corrosive and dangerous when wet. Handle this chemical only with gloves, and be sure to read over the MSDS before using. Maintain good and proper lab techniques. We are working with some nasty stuff in this lab. We need to perform this lab outdoors if possible, or indoors with lots of ventilation. The reaction advances in stages:

Bubbles in the burette tell us the reaction is occurring.
Brown streaks will appear in the water contained in the glass jar as gas collects there.
Brown vapor will begin to appear in the test tube. When the reaction is complete, the test tube will contain lots of brown vapor.

After we produce HBr, we will perform a number of tests to see if it is an acid or a base.

Test contents of test tube with blue litmus paper. Red color change indicates an acid.
Add baking soda to the HBr. Bubbles and the solution turning white. HBr is an acid in this test because it is obviously reacting with a base.
If a magnesium strip placed in the HBr corrodes, or starts to dissolve, then HBr is an acid.
With the addition of silver nitrate to the HBr, if a white cloudiness occurs and crystals form in the bottom of the test tube, then HBr is an acid.

C3000: Experiment

Download Student Worksheet & Exercises Here’s what’s going on in this experiment: KBr + NaHSO₄ --> HBr + KNaSO₄ Potassium bromide and sodium hydrogen sulfate, when heated, produce hydrogen bromide and potassium sodium sulfate. Cleanup: We are going to clean everything thoroughly after we finish the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. After washing, chemists rinse out all visible soap and then rinse three times more. Storage: Place cleaned tools and glassware in their respective storage places. Disposal: Liquids can be washed down the drain. Solids are thrown in the trash.

Click here to download Homework Problem Set #9.

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Hydrogen Chlorine Gas

Friday November 18, 2011

WARNING!! THIS EXPERIMENT IS PARTICULARLY DANGEROUS!! (No kidding.) This experiment is for advanced students.

We’ve created a video that shows you how to safely do this experiment, although if you’re nervous about doing this one, just watch the video and skip the actual experiment.

The gas you generate with this experiment is lethal in large doses, so you MUST do this experiment outdoors. We’ll be making a tiny amount to show how the chemical reactions of chlorine and hydrogen work.

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Hydrochloric acid is a strong acid. It is highly corrosive, which means that this acid will destroy or irreversibly damage another substance it comes in contact with. Simple terms….it is pretty nasty, so take special care when working with or around it.

HCl is used in processing leather, cleaning products, and in the food industry. We are most familiar with HCl in the form of Gastric Acid. HCl is in gastric acid and is one of the main ingredients in our stomach to aid in digestion of our food. In our lab we will produce hydrogen chlorine gas and add water to turn change it into hydrochloric acid.

Materials:

Glass jar
90⁰ bend glass tubing
One-hole rubber stopper
Chemistry stand
Wire mesh
2 Test tubes
Test tube clamp
Alcohol burner
Lighter
Tripod stand
Sodium hydrogen sulfate (MSDS) Sodium hydrogen sulfate is very toxic. Respect it, handle it carefully and responsibly. Do not take it for granted.
Salt
One-hole cork
Medicine dropper
Water
Solid rubber stopper

Perform this experiment outdoors. If that is not a possibility, and you must do it inside, open doors and windows to provide lots of ventilation. Hydrogen chlorine gas inhalation can be fatal, but we are only producing a very small amount.

There are many steps in this lab, so go slow and steady. Read the lab over several times so you are sure what is going on and what is happening next.

When we shake the sodium hydrogen sulfate and the salt together in a stoppered test tube, we are trying to produce a heterogeneous mixture. Heterogeneous is a scientific word that means substance are mixed all together to be as one. A sample taken from one spot in the mixture should be the same as a sample taken from any other spot in the mixture.

At some point in this lab, we need to point the test tube containing the reaction slightly down. This is so the hydrogen chlorine gas can flow downhill. The gas is denser than air, so it will sink to the bottom of anything air filled…..like a room or a test tube.

Hydrogen chloride gas is poisonous – DO NOT INHALE!

When the medicine dropper / cork tool is placed in the water, water will be sucked up into the test tube. The water combines with the hydrogen chlorine gas to create hydrochloric acid.

A double replacement chemical reaction will take place in this experiment. A free hydrogen ion (+) and a free sodium ion (+) will be produced. Because their charges are alike, they cannot bond, but they can take each other’s place. The spots they each left are negatively charged after the hydrogen and sodium have departed. Opposites attract, and they reorganize into a double replacement reaction.

C3000: Experiment

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

NaCl + NaHSO₄–> HCl + Na₂SO₄

Salt is combined with sodium hydrogen sulfate and heated to produce hydrochloric acid and sodium sulfate

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Our HCl needs to be neutralized before disposal. Put a bit of baking soda into the test tube. The contents should bubble as the neutralization is taking place. After neutralization, the liquid is safe, and can be washed down the drain. Solids are thrown in the trash.

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Robotic Hand

Tuesday November 15, 2011

Your body moves when muscles pull on the bones through ligaments and tendons. Ligaments attach the bones to other bones, and the tendons attach the bones to the muscles.

If you place your relaxed arm on a table, palm-side up, you can get the fingers to move by pushing on the tendons below your wrist. We’re going to make a real working model of your hand, complete with the tendons that move the fingers! Are you ready?

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Here’s what you need:

five flexible straws
scrap of cardboard (at least as big as your hand)
five rubber bands
5 feet of string or thin rope (and a lighter with adult help if you’re using nylon rope)
hot glue with glue sticks
scissors
razor

Download Student Worksheet & Exercises

Exercises

What types of muscles are connected to our bones?
Which type of connective tissue connects our muscles to our bones?
What do extensor tendons in our wrist do?
What do flexor tendons do?

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Chemical Fingerprinting

Tuesday November 15, 2011

Did you know that the patterns on the tips of your fingers are unique? It’s true! Just like no two snowflakes are alike, no two people have the same set of fingerprints. In this experiment, you will be using a chemical reaction to generate your own set of blood-red prints.

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Here’s what you need

1 oz. bottle of baking soda or sodium carbonate (washing soda)
water
1 sheet of goldenrod paper
1 paper towel
1 magnifying lens

Download Student Worksheet & Exercises

Here’s what you do

Pour a couple teaspoons of the baking soda (sodium carbonate) into a cup of water. Swish your right index finger in the damp baking soda and then roll that finger on the goldenrod paper. This should leave a bright red fingerprint on the paper. Label it right index.
Continue the procedure for each finger on both hands to make a full set of prints. Be sure to label each fingerprint as you make it to identify which print goes to each finger. Don’t forget to make prints of your thumbs!
Compare your prints to the basic patterns in the guide. Check for features such as whorls or loops and label them appropriately on your prints. Use abbreviations such as A for accidental, PW for plain whorl, and DL for double loop.
After you have identified the dominant pattern on each of your fingertips, prepare a simple chart for each hand to record the data by finger.
When you are finished studying your own prints, ask a volunteer to let you make prints of their fingers.

What’s going on?

Goldenrod paper is made using phenolphthalein, a chemical that turns red when exposed to materials with relatively high pH. Baking soda (or sodium bicarbonate) is a base which has a pH of about 8.5. Rolling your baking soda covered fingers on the goldenrod paper creates a chemical reaction which produces a red fingerprint.

Exercises

What are the three main types of patterns on fingerprints? Describe each.
How do fingerprints have the potential to help solve crime?
Why does baking soda (or washing soda) show up red on the paper?
What kind of pH do bases have?
What kind of reaction do we see when the red fingerprints show up on the paper?

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Eyeballoon

Tuesday November 15, 2011

In this lab, we are going to make an eyeball model using a balloon. This experiment should give you a better idea of how your eyes work. The way your brain actually sees things is still a mystery, but using the balloon we can get a good working model of how light gets to your brain.

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Here’s what you need

- 1 biconvex plastic lens
- 1 round balloon, white, 9 inches
- 1 assistant
- 1 votive candle
- 1 black marker
- 1 book of matches
- 1 metric ruler
- Adult Supervision!

Download Student Worksheet & Exercises

Here’s what you do

Blow up the balloon until it is about the size of a grapefruit. If it’s difficult to inflate, stretch the material a few times or ask an adult to help you.
You will need an extra set of hands for this portion. Ask your partner to hold the neck of the balloon closed to keep the air in while you insert the lens into the opening. The lens will need to be inserted perpendicularly to the balloon’s neck. It will prevent any air from escaping once it’s in place. Like your eye, light will enter through the lens and travel toward the back of the balloon.
Hold the balloon so that the lens is pointing toward you. Take the lens between your thumb and index finger. Look into the lens into the balloon. You should have a clear view of the inside. Start to twist the balloon a little and notice that the neck gets smaller like your pupils do when exposed to light. Practice opening and closing the balloon’s “pupil.”
Have an adult help you put the candle on the table and light it. Turn out the lights.
Put the balloon about 20 to 30 centimeters away from the candle with the lens pointed toward it. The balloon should be between you and the candle. You should see a projection of the candle’s flame on the back of the balloon’s surface. Move the balloon back and forth in order to better focus the image on the back of the balloon and then proceed with data collection.
Describe the image you see on the back of the balloon. How is it different from the flame you see with your eyes? Draw a picture of how the flame looks.
The focal length is the distance from the flame to the image on the balloon. Measure this distance and record it.
What happens if you lightly push down on the top of the balloon? Does this affect the image? You are experimenting with the affect caused by near-sightedness.
To approximate a farsighted eye, gently push in the front and back of the balloon to make it taller. How does this change what you see?

What’s going on?

Okay, let’s discuss the part of the balloon that relate to parts of your eye. The white portion of the balloon represents your sclera, which you may have already guessed is also the white part of your eye. It is actually a coating made of protein that covers the various muscle in your eye and holds everything together.

Of course, the lens you inserted represents the actual lens in your eye. The muscles surrounding the lens are called ciliary muscles and they are represented by the rubber neck of your balloon. The ciliary muscles help to control the amount of light entering your eyes.

The retina is in the back of your eye, which is represented by the inside back of your balloon. The retina supports your rods and cones. They collect information about light and color and send it to your brain.

Exercises

How does your eye work like a camera?
How can you tell if a lens is double convex?
What is the difference between convex and concave?
Can you give an example of an everyday object that has both a convex and a concave side?
How can you change the balloon to make it like a near-sighted eye?
How can you change the balloon to make it like a far-sighted eye?

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Mapping your Tongue

Tuesday November 15, 2011

The tongue has an ingenious design. Receptors responsible for getting information are separate and compartmentalized. So, different areas on the tongue actually have receptors for different types of tastes. This helps us to separate and enjoy the distinct flavors. In this experiment, you will be locating the receptors for sweet, sour, salty, and bitter on the tongue’s surface.

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Here’s what you need

4 cotton swabs
5 wax cups
1 bag of black tea
1 bottle of red vinegar
2 packages of sugar
2 packages of salt
1 microwave
water
1 spoon
1 partner
1 blindfold

Download Student Worksheet & Exercises

Here’s what you do

1. Put 3 ounces of water into the first of the wax cups. Bring it to a boil in the microwave and have an adult help you add a teabag. This will make your bitter cup. Let it sit for 5 minutes. While it is steeping, you can prepare the other cups.

2. Fill the remaining cups with 2 ounces of water each. Prepare them as follows:

A.      For the sweet cup, add two packages of sugar to the warm water in one of the cups. Stir until well dissolved.
B.      For the sour cup, add 2 ounces of red vinegar to another cup and stir well.
C.      For the salty cup, put two packages of salt into the final cup. Stir until dissolved.
D.      The last step in cup preparation is to discard the tea bag that has been steeping in the first cup.

3. Now put the blindfold on your partner and have them stick out their tongue. Dip the first swab into the tea. Using the diagram as a guide, swab each area one at a time: A, B, C, and D. Ask your partner to identify the flavors as sweet, sour, salty, bitter, or can’t tell as you swab each individual area. Record your partner’s response for each area.

4.Your partner should rinse out their mouth with water after testing the bitter tea. Then test each of the remaining solutions, one at a time in the same manner.

What’s going on?

Humans can identify thousands of distinct tastes, but we only have four types of taste receptors. When you take a bite of something flavorful, your saliva starts to dissolve it immediately. This solution of flavor and saliva goes to your taste buds and is then interpreted by your brain as sweet, sour, salty, or bitter.

The taste buds have taste receptors which bind to the structure of certain molecules: sweet receptors recognize hydroxyl groups (OH) in sugars, sour receptors find acids (H+, such as the citric acid in a lemon), salt receptors respond to metal ions (like Na+ in table salt), and bitter receptors are triggered by alkaloids. These are bases which contain nitrogen. It’s interesting to note the location of the bitter taste buds – they are on the back of the tongue. Since many poisons are alkaloids, their bitter taste may actually trigger vomiting.

Anyone who’s had a stuffy nose can tell you that smell plays a big role in our ability to taste. This makes sense because we know that we can only really taste the 4 distinct true flavors of sweet, sour, salty, and bitter. Our nose works in partnership with our tongue to allow us to identify more complex flavors.

Exercises

How many different types of taste receptors do we have? What are they?
Can you still taste food when you have a stuffy nose?
Which taste receptors recognize the hydroxyl group?

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Scent Matching

Tuesday November 15, 2011

We now know that odor molecules are diffused throughout a room by the motion of air molecules, which are constantly moving and bumping into them. We also know that warm air moves faster than cold air, and that increasing the movement of the air (like with a fan) will increase the diffusion process.

In this experiment, we look at what happens when the odor molecules find their way into your nose. Your nose has smell cells located in a small area called the olfactory epithelium. We will use them here to match smells with other smells.

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Here’s what you need

- 10 small containers with lids
- 10 cotton balls
- 1 bottle of lemon juice
- 1 cup of black coffee
- 1 bottle of vanilla extract
- 1 bottle of cinnamon oil
- 1 bottle of soy sauce
- 1 black felt marker
- 1 assistant

Download Student Worksheet & Exercises

Here’s what you do

Take the lids off of the containers and number the first five with a 1 through 5. Mark the other five with A through E.
Put a cotton ball into each container. Start with the numbered containers and add some lemon, coffee, cinnamon, soy sauce, and vanilla. Record the smell for each number for reference.
Fill the lettered containers with the same liquids, but not in the same order. Be sure to record the material you have used for each letter.
Take the closed containers to your assistant. Ask them to match the scent in the first canister with the proper lettered container without opening the container. Given them permission to roll, drop, and shake the containers, but they can’t be opened. Note their response – are they correct?
Repeat step 4 for each of the containers until they all have been matched. Then check your recorded data and see how well your assistant did with matching.

What’s going on?

Everything here produces a distinct odor. The smells go into your nose where they are interpreted by the tiny hair-like smell cells in your olfactory epithelium. The smell cells work together to distinguish smells and then send the interpreted information to the brain for recognition.

We previously noted that humans have an average of 10,000,000 smell cells, but they aren’t all the same. You have about 20 different types and each detects a specific type of odor. The types work together and your brain translates their signals as a unique odor.

Exercises

What is the scientific name for sense of smell?
What is the name of the tissue which helps the brain to distinguish between smells?

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Detective Boxes

Tuesday November 15, 2011

In addition to looking pretty neat with all those loops and whirls, your fingertips are great at multitasking. The skin on them has a ton of receptors that help us to gather a lot of information about our environment such as texture, movement, pressure, and temperature.

This experiment will test your ability to determine textures by using touch receptors. You will use shoeboxes with holes cut into them to make texture boxes. Each box will have a textured surface that you can feel, but not see. Through the receptors in your fingers, you will determine whether the surface is rough, waxy, soft, or smooth.

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Here’s what you need

4 shoeboxes with lids
1 soup can
1 pencil
1 pair of scissors
1 sheet of sandpaper
1 sheet of wax paper
1 sheet of flannel fabric
1 sheet of plastic
1 glue gun
1 pair of gloves
partners

Download Student Worksheet & Exercises

Here’s what you do

Using the soup can as a guide, draw a circle at the end of a shoebox. Then use the scissors to cut out the circle.
Cut a piece of sandpaper to fit the bottom of the shoebox (a ruler might also be handy to get an exact measurement). Glue the sandpaper to the inside bottom of the shoebox. Put the lid on the box and label it as Box 1.
Repeat the first two steps for each of the boxes, putting the wax paper, flannel, and plastic in boxes 2-4. Be sure to label each.
Now ask a partner to reach into each box, feel the texture, and describe it as rough, waxy, soft, or smooth. Record their answer. Use undecided if they aren’t sure.
Once your friend has identified a texture and you have recorded their response, open the box so that you can both see what material they have evaluated. Be sure to note in your data whether your friend was correct with a Y or N. Repeat steps 4 and 5 for each of the boxes.
Have your friend leave the room or look away so that you can rearrange the box lids. Then give them the gloves to wear and repeat the test using gloved hands. Record the data and compare the effectiveness of gloved hands. Does this have an impact on the touch receptors?

What’s going on?

The fabric of the gloves interferes with the ability of our touch receptors to function fully. Our fingertips are feeling the fabric of the gloves on their receptors and this makes it difficult to perceive what they are touching through the gloves.

We have 5 different types of receptors. They are types of nerve endings in our skin and are connected to our brains.

The ones that respond to deep pressure are called Pacini’s endings and they are embedded deep in our skin.
Merkel’s endings detect moderate pressure.
Meissner’s ending respond to vibrations and light pressure.
Ruffini’s ending, which detect changes in temperature, can also respond to pressure.
Our pain receptors are called free endings.

Exercises

Name, in order, the three main layers of skin.
Which layer of skin contains the mechanoreceptors? Name two more items in this layer.
Name the five types of nerve endings and their specialization.

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Tasty Tastebuds

Tuesday November 15, 2011

Did you know that your tongue can taste about 10,000 unique flavors? Our tongues take an organized approach to flavor classification by dividing tastes into the four basic categories of sweet, sour, salty, and bitter.

For this experiment, you will need a brave partner! They will be blindfolded and will be attempting to guess foods. Relying only on their sense of taste, they will try to determine what kind of foods you are giving them.

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Here’s what you need

1 partner
1 blindfold
1 cup of water
1 plate
1 lemon
2 toothpicks
1 sugar cube
1 salty cracker
1 piece of dark chocolate
1 pencil

Download Student Worksheet & Exercises

Here’s what you do

(NOTE: Make sure your partner is not around for the first step!) Prepare a plate with a piece of lemon on a toothpick, a sugar cube, a really salty cracker, and a piece of dark chocolate, which will also be on a toothpick.
Blindfold your partner before they see the plate. Explain that you’re going to give them food samples. Their job is to taste each sample, one at a time, and then determine whether the food is sweet, sour, salty, or bitter. After they have provided a category, see if they can tell you the specific flavor of the food. They should use the water between samples in order to rinse their mouth and prepare for the next food.
Record data and observations for each individual food item. Be sure to list each food, your partner’s group classifications (sweet, sour, salty, or bitter) and what specific flavors that they note.

What’s going on?

When you put food in your mouth, saliva immediately begins to break it down. Saliva mixes with food and makes a solution, which then takes the food (and its flavor) to the taste pores. There, receptors determine the chemical structure and send this information to your brain, which then decodes and categorizes the taste. The exact nature of the secret code relayed between your taste receptors and your brain is still a mystery. Maybe someday you can help to figure out the science behind it!

Did you know that humans have about 7500 taste buds? That’s a lot compared to most chickens, which only have about 24, total. But it’s a pretty small amount compared to catfish. They have over 175,000 taste buds! Can you imagine what your favorite dessert might taste like if you had that many? I wonder if it would be a good thing, or maybe too much information. Perhaps we are better off with our own perfect number of taste buds!

Exercises

How does saliva help with tasting?
What helps to decode the chemical structure of a food so that the brain can determine its taste type?
Why do foods sometimes become less strong as we age?

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Detecting Temperature Changes

Tuesday November 15, 2011

This experiment has two parts. For the first half, you will mix two chemicals that will produce heat and gas. The temperature receptors in your skin will be able to detect the heat. Your ears will detect the gas at it vibrates and escapes its container.

In the second portion you will demonstrate a characteristic in a chemical reaction. For this experiment, it will be an endothermic reaction, which is the absorption of heat energy. This type of reaction is easy to notice because it makes things cold to touch. The chemical you will be using, ammonium nitrate, is actually used in emergency cold packs.

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Here’s what you need

1 measuring cup
1 bottle of calcium chloride
1 bottle of ammonium nitrate
2 resealable baggies
water

Download Student Worksheet & Exercises

Here’s what you do

Put about ½ cup of warm water in one of the baggies.
Add about a third of an ounce of calcium chloride to the water. Close the baggie and start to roll around the pellets with your fingers. As they start to dissolve, the chemical also starts to increase the temperature of the water.
Now dispose of these ingredients down the drain. Flush with lots of running water.
Open the ammonium nitrate and fill its cap with pellets. Put these in the second baggie.
Start to pinch the ammonium nitrate through the plastic bag and check for a temperature change. Does anything happen in the absence of water?
Now put a small amount of water (about room temperature) into the bag. Fill it about ¼ of the way full.
Hold the bottom of the bag with both hands and begin to rock it back and forth a bit. This should start to dissolve the pellets. With your hands on the water, you should start to note a temperature decrease. If this doesn’t work, roll the pellets around as you did with the calcium chloride.
When you are finished, you can pour the contents out on to brown spot of grass (because ammonium nitrate is a main ingredient in many fertilizers). Or if you would prefer, just empty the contents down the drain.

What’s going on?

Calcium chloride splits into calcium ions and chloride ions when it is mixed with water. As this occurs, energy is released in the form of heat. This is the same heat energy you felt when holding the baggie and rubbing the pellets.

Adding ammonium nitrate to water causes both its ammonium and nitrate ions to dissolve, which results in heat absorption as iconic bonds are broken. This is an endothermic reaction.

The point of both of these experiments is that the Ruffini’s endings in your skin are what allow the heat and/or cold data to be collected and sent to your brain for translation.

Your skin has many other parts in addition to its receptors. Some examples include hair, blood vessels, and sweat glands. Blood vessels and sweat glands respond to heat and cold, helping to control your body’s temperature. You are probably familiar with how sweat glands help to cool you down (evaporation), but how about blood vessels? As an example, if you run around outside on a hot day, your cheeks get red because the blood vessels on your skin’s surface have dilated, which brings more blood to the surface and allows the body to cool its insides a bit.

Exercises

Which chemical when mixed with water was an endothermic (absorbed heat and felt cold) reaction?
Which chemical resulted in an exothermic reaction (gave off heat)? Why does this happen?
What are ways that the human body can detect temperature?

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Rubber Eggs

Tuesday November 15, 2011

This lab has two parts. First, you will learn a bit about how specific chemicals react in a specific manner. And next, you will learn a bit of biology: the structure of bird bones and the minerals that compose them.

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Here’s what you need

- 4 fresh chicken wing bones, meat removed
- 1-16 oz. bottle of distilled white vinegar
- 2-12 oz. plastic cups
- 1 fresh egg
- 1 spoon

Click here to download the student worksheet.

Here’s what you do

Make sure all the meat and cartilage is gone. Check near the joints for soft, white-gray matter and clean it off. Now break a bone in half. What does the inside look like? Note the color and hardness for your data. Be sure to wash your hands well after studying the bones.
Pour some vinegar in a cup and gently place the bones in the solution. Add more to cover the bones, if needed. Put the cup in a spot where it won’t be disturbed for a few days. It will take a while for the vinegar to fully react with the bones.
Take a look at the egg and note its color and hardness in your experiment data. Now carefully place the fresh egg in the second cup and pour vinegar over it. Be sure to completely cover the egg. You will need to cover the egg or keep an eye on it. The vinegar will evaporate and will need to be replenished. This portion of the experiment will take around 24 hours.
Use the spoon to remove the egg after 24 hours has passed. Set it down and gently push on it. What happened to the part that used to be shell? Check your notes from the previous day and note any changes that have occurred in the color and hardness of the egg after it has been in the vinegar.
After a few more days, take the chicken bones out of the vinegar. Bend them and see what happens. Do they break as easily as they did the first day? Look at your data and compare the color and hardness of the bones now to how they looked on the first day. Record the changes you observe.

What’s going on?

Calcium is the mineral in both bones and eggshells that makes them hard. Putting the bones and egg in vinegar caused the calcium to begin to react. Vinegar leached calcium from both the bones and the shell, which caused their hardened structure to become weak.

Did you know that your bones and teeth contain 99% of the calcium in your body? About ¾ of your bones are compact, but the remaining ¼ of them is spongy. But do you think your bones or your teeth are harder? The second hardest material in your entire body is the compact, hard bone. Your teeth enamel is actually the hardest material.

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Water Lens

Tuesday November 15, 2011

Like sound, light travels in waves. These waves of light enter your eyes through the pupil, which is the small black dot right in the center of your colored iris. Your lens bends and focuses the light that enters your eye. In this experiment, we will study this process of bending light and we will look at the difference between concave and convex lenses.

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Here’s what you need

1 washer, 3/8 inch inside diameter
1 microscope slide
1 container of petroleum jelly
1 piece of newsprint with a lot of type
1 pipette, 1 mL
water

Download Student Worksheet & Exercises

Here’s what you do

Apply a little petroleum jelly on the washer’s flat side. NOTE: washers have flat and founded sides, so be sure you are putting the petroleum jelly on the flat side of the washer.
Put the washer, petroleum jelly side down, on the middle of the microscope slide. Twist the washer a bit to seat it on the slide and make a seal. This should keep the water in place.
Put the washer and slide on the newsprint. Fill the pipette with water. Use the pipette to slowly place water in the washer. Fill the washer until the water makes a domed shape. You have just made a convex lens!
Find a letter e on the newspaper and put the lens over it. Draw a diagram of what the e looks like through the convex lens.
Now use the pipette to remove water from the washer. Your goal is to create a dip in the surface of the water. Now find the same e and place your new concave lens over the letter. Draw a picture of what the e looks like through the new lens.

What’s going on?

You can see that a convex lens bends outward and a concave lens bends inward. What does this do to light?

In a convex lens, the domed surface means that if light waves come in through the flat bottom surface, they will be spread out, or refracted, as they exit the curved portion of the lens. But since a concave lens dips inward it creates the opposite effect. When light waves exit the concave surface, they are brought together. This makes images appear smaller.

The lens does all the focusing work but it is actually the shape of the eye that determines what you see. If you have a tall, oblong eye, you are far-sighted. And conversely, if your eyes are short and fat, you are near-sighted. In either case, the lenses are functioning properly but the actual shape of the eye needs a slight adjustment.

Exercises

What are the two main types of lenses?
How are the two main types of lenses shaped
How do the two main types of lenses work?

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Foggy Hands

Tuesday November 15, 2011

Skin has another function that it vital to your survival: temperature regulation. Being exposed to high temperatures causes your skin’s pores to open up and release sweat onto your body. This helps cool us off by the resulting process of evaporation.

Your pores will close in extremely cold temperatures. Also, the body stops blood flowing to the skin in order to conserve heat for the important vital organs and their processes.

In this lab, we study the moisture that your skin produces – even when you are not aware of it!

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Here’s what you need

1 gallon baggie
1 string, 12 inches long
1 assistant
1 clock

Download Student Worksheet & Exercises

Here’s what you do

Record a description of how moist your hand is prior to putting it in the baggie. This is at 0 minutes.
Put your hand in the baggie and ask your assistant to tie it closed around your wrist. No air should be able to get in or out of the baggie. Record the time for tracking purposes.
Check your hand every 10 minutes for a half hour. With each observation note the amount of moisture that has accumulated. Record your observations at 10 minutes, 20 minutes, and 30 minutes.
What do you think will happen if you go outside and run around with your hand inside the bag? Try it and see if it accelerates the process.

What’s going on?

Sweat glands are always producing moisture on our skin. Most of the time, we don’t really notice this process. By enclosing your hand in plastic, this moisture can’t evaporate as it normally would. The bag collects and condenses it.

It is interesting to note that your body can produce up to a gallon of water in extremely hot temperatures – 110 degrees Fahrenheit and higher. This is one of the reasons it’s so important to stay hydrated in extreme heat!

Exercises

How is sweat released from the body through the skin?
How does sweat help to cool the body?
What did you observe at the 30 minute mark in your experiment?
What is evaporation and how is it different from condensation?

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Finger Thermometers

Tuesday November 15, 2011

Your fingers have receptors which perform various jobs. In addition to touch, they can detect pressure, texture, and other physical stimuli. One specialized type of receptors is called Ruffini’s receptors. They are good at identifying changes in pressure and temperature. In this experiment, we will test their ability to distinguish between hot and cold temperatures. We are actually going to try and trick your Ruffini endings. Do you think it will work?

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Here’s what you need

3 glasses
1 Celsius/Fahrenheit thermometer
hands
1 clock with second hand
hot water
cold water
ice cubes (optional)
room-temperature water

Download Student Worksheet & Exercises

Here’s what you do

Place the three glasses in front of you on a table. They should be in a row: left, middle and right.
Put hot water from the faucet into the first glass on your right. Pour very cold water from the tap into the far left glass. You can even add a couple of ice cubes if you have them available. Finally, fill the glass that is in the middle with room temperature water.
Now use your right hand to hold on to the glass on the right with hot water. Really spread out your fingers and wrap them around the glass. Do the same thing with your left hand and the glass filled with cold water. Be sure to check the clock and leave your hands on the glasses for exactly one minute.
After one minute, take your hands and put them both on the middle glass. (You may need to stack one on top of the other if your glasses are narrow). Note the temperature you feel with each hand: hot, cold, or medium. You can use the thermometer to record the actual water temperature.
Now repeat steps 1-4. This time, switch the hot and cold glasses so that you are holding the hot water with your left hand and the cold water with your right hand. Compare these results with your initial results. Do both hands respond in a similar way or is one more sensitive that the other?
Some questions to think about:

Does the temperature of the middle glass feel warmer, cooler, or the same when you touch it with your hand that was holding the warm glass?
What does your hand that was touching the cold glass feel when it touches the middle glass?
What do you feel when both hands are on the middle glass?
Why do you think your hands are not the best instruments for determining temperature?

What’s going on?

Your hands are designed to adapt to temperature. Touching the warm glass relaxes the muscles of your hands, increases circulation, and enhances flexibility. When your hand touches the cold glass the cells on your skin’s surface begin to contract to minimize loss of heat and your hand becomes less flexible. Then, when you grab the middle can your hands get a bit confused. Relatively speaking, the middle glass feels warmer to the hand that was holding the cold glass and it feels cooler to the hand that was holding the warm one. The hands are still feeling the temperature, but your brain gets confused.

Did you know that our skin does not have receptors to indicated burning hot? This sensation is actually created by three different receptors which fire at the same time: pain, cold, and warm. This explain why to some people, very hot things actually feel cold. If you could prepare a group of alternating hot and cold metal bars, touching them with your fingers would be an odd experience. Your brain will think they are too hot to touch and will tell you to pull away your hand!

Exercises

Does the temperature of the middle glass feel warmer, cooler, or the same when you touch it with your hand that was holding the warm glass?
What does your hand that was touching the cold glass feel when it touches the middle glass?
What do you feel when both hands are on the middle glass?
Why do you think your hands are not the best instruments for determining temperature?
Which nerve endings help to detect changes in temperature?

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Disappearing Frog Experiment

Tuesday November 15, 2011

Your optic nerve can be thought of as a data cord that is plugged in to each eye and connects them to your brain. The area where the nerve connects to the back of your eye creates a blind spot. There are no receptors in this area at all and if something is in that area, you won’t be able to see it. This experiment locates your blind spot.

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Here’s what you need

- 1 frog and dot printout
- 1 meter stick
- 1 scrap piece of cardboard

Download Student Worksheet & Exercises

Here’s what you do

Print out the frog and dot and remove the dotted portion. Attach it to the piece of cardboard, which should have a matching portion removed. You can place the paper and cardboard on the meter stick at the notched area.
Now to locate blind spots. First, close your left eye. Look at the frog with your right eye. Can you see the dot and the frog? You should be able to see both at this point, but concentrate on the frog. Now slowly move the stick toward you so that the frog is coming toward your eye. Pay attention and stop when the dot disappears from your peripheral vision. At this point, the light hitting the dot and reflecting back toward your eye is hitting the blind spot at the back of your right eyeball, so you can’t see it. Record how far your eye is from the card for your right eye.
Continue to move the stick toward your face and at some point you will notice that you are able to see the dot again. Keep moving the stick forward and back. What happens to the dot?
Repeat steps 2 and 3 with your left eye, keeping your right eye closed. This time, stare at the dot and watch for the frog to disappear. Move the paper on the stick back and forth slowly until you notice the frog disappears. You have found the blind spot for your left eye. Be sure to note the distance the paper is from your eye.

What’s going on?

There are no light receptors in the area of your eye where the optic nerve attaches to your eyeball. This is your blind spot and if an image is in this spot, the light reflected off of it doesn’t get perceived by your eye. So you don’t see it!

Exercises

What did you notice about the vision of the student and the blind spot that you measured?
Why do you think it’s important to know where your blind spot is?

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Swallowing

Tuesday November 15, 2011

Peristalsis is the wavelike movement of muscles that move food through your gastrointestinal tract. The process of digestion begins with chewing and mixing the food with saliva. From there, the epiglottis opens up to deposit a hunk of chewed food (called bolus) into your esophagus – this is the tube that runs from your mouth to your stomach. Since the esophagus is so skinny, the muscles along it must expand and contract in order to move food down. In this activity we will examine that process.

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Here’s what you need

- 1 tennis ball
- 1 pair of old nylons
- 1 pair of scissors

Download Student Worksheet & Exercises

Here’s what you do

Cut away the control top portion of the nylons and remove the toe part as well (have an adult help you, if needed). You should now have a long piece of nylon.
Put the tennis ball in one end of the nylon “esophagus.” Start using both hands to move the ball down the nylon tube until it arrives at the other end.

What’s going on?

The esophagus is lined with muscles that work in waves, expanding and contracting to move food along it down into the stomach. These are very strong muscles: even if you ate upside down they would work!

In the grand scheme of the digestion process, the role of the esophagus is important, but relatively short. It takes about 10 seconds to move food from the mouth to the stomach, but the entire process of digestion can take up to 2 and a half days to finish!

Exercises

What is the tube called that connects the mouth and stomach?
What is the process called that moves food along the digestive tract and how does it work?
How long is food in the esophagus?

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Diffusion

Tuesday November 15, 2011

Everything living produces some sort of odor. Flowers use them to entice bees to pollinate them. We know that the tastes of foods are enhanced by the way that they smell. As humans, each of us even has own unique odor.

In this lab, we look at the diffusion of scents. They start in one place, but often end up spread around the room and can be detected by many people.

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Here’s what you need

- 1 onion
- 1 lemon
- 1 bottle of ground cinnamon
- 1 clove of fresh garlic
- 1 garlic press
- 1 pile of fresh coffee grounds
- 1 kitchen knife
- 1 cutting board
- 1 variable-speed fan
- 1 clock with a second hand

Download Student Worksheet & Exercises

Here’s what you do

Start in a room big enough so that you can prepare the foods at one end and your friends or family members can be at the other end, but positioned so they can’t see what you’re doing.
You will need a simple map of the room showing the locations of your partners, the source of the odor, and the fan (which will help with the scent diffusion). Create a new map for each smell.
Turn on the fan and begin with the onion. Ask an adult to help you with cutting the onion into several small pieces. Be sure to hold the chopped pieces up in front of the fan. Ask your partners to raise their hands when they smell the onion. If they don’t smell it, they can leave their hands down. Note on the onion map where its smell is detected. Indicate with a line the farthest area where the onion is smelled. This is its leading edge.
Check in with your partners once per minute for five minutes. Ask them to raise their hands and repeat the process of noting the areas where the smell is detected. Each time you check, draw a line to indicate the farthest area the smell reaches. This will give you an idea of how fast and how far the smell diffused.
Repeat steps 3 and 4 with each item: cut and smash the lemon and press the garlic. Which odors travel the farthest? Which ones travel the fastest?

What’s going on?

Many factors affect how quickly odors diffuse. First, the air is constantly moving. As the air molecules in the room are colliding with each other (and with the odor molecules) they help to move the smells farther through the room. Second, the fan makes a huge difference. It accelerates the natural process of air and odor molecules and moves them much farther and faster than they would go otherwise. Finally, the air temperate plays an important role. If the temperature is higher, the air and odor molecules will move faster.

As humans, we can boast about 10,000,000 smell cells in our noses. This seems pretty impressive…unless you compare us to canines. Dogs have over 200,000,000 smelling cells in their nasal cavities!

Exercises

Which odors travel the farthest?
Which ones travel the fastest?
Why do we use the fan?
Does air temperature matter?

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Cooling and Heating

Tuesday November 15, 2011

In this experiment, we will continue to explore Ruffini’s endings in your skin. We also look at your body’s ability to detect temperature and regulate its own temperature. You will study how the body cools and warms itself.

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Here’s what you need

1 bottle of rubbing alcohol
1 cotton ball
1 liquid crystal thermometer strip
1 cotton glove

Download Student Worksheet & Exercises

Here’s what you do

Position the thermometer strip on the back of your hand. Give it a moment to register the temperature of your body. Record this temperature as a base reading for your data.
Put some rubbing alcohol on a cotton ball. Now use the cotton ball to wipe the alcohol on the surface where you took the reading, right on the back of your hand. Quickly put the thermometer strip right back on the spot where you have put the alcohol and take another reading. Note the temperature in your records.
Now put the glove on your hand and run around in the yard, do some jumping jacks, or find another way to be physically active for 3 minutes. When you have worked up a sweat, come back to the experiment area. With your hand still in the glove, put the liquid crystal thermometer on the back of your hand where you took the first reading. Record this temperature information in your data records.
Finally, take off the glove and observe your hand. Can you tell that your sweat glands have been working? If so, have they been very active or just a little active?

What’s going on?

Your body likes to keep your temperature in equilibrium, which is a state of balance. It works hard to regulate your temperature and avoid any sudden changes that could be harmful. Constant and predictable is your body’s goal and it uses your skin to help.

When you are cold, blood flow to the skin is reduced in order to help stem the loss of heat. Your hair also stands on end in an error to trap air next to the body and help insulate it…although this doesn’t work very well for most of us! This is a more effective tool against heat loss with much furrier mammals.

In order to cool you down, skin can use some of your three million sweat glands. Sweat absorbs and displaces extra heat and can also close openings to cells on the surface to avoid excess gains in heat.

Your data in the lab should have simulated the effects of body temperature in three different conditions: equilibrium, excess cold, and excess heat.

Exercises

What is equilibrium?
How does equilibrium relate to body temperature?
How does our body help to cool us down?

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Visual Reflex

Tuesday November 15, 2011

Voluntary nerves are the ones that are under our direct control. Others, called involuntary nerves, are under the control of our brains and create involuntary reactions.

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Here’s what you need

- 1 metric ruler
- 5 volunteers

Download Student Worksheet & Exercises

Here’s what you do

You will begin by testing your visual reflexes with the help of an assistant.
Hold your right elbow at your waist. Position your arm so that it is parallel to the floor. Make a space of about an inch by holding your thumb and forefinger apart. Ask your assistant to hold the ruler vertically, above your thumb and finger.
Your job is to focus on the ruler. Your partner will unexpectedly release it so that it begins to fall. You will attempt to catch the ruler as soon as you possibly can.
Repeat the experiment 5 times, recording the time it takes to catch the ruler each time for your data. Use the times you record to find your average time.
Try this experiment for 5 additional people. Find the average reaction speed of each person and the average speed of the group as a whole.

What’s going on?

This experiment is an example of a voluntary response. Your eyes see the ruler moving and tell your brain, which then tells your fingers to close quickly. This all happens very fast, but involuntary reflexes can be much faster! You may notice in this activity that the ruler falls over half of the way through your fingers before you can stop it. This is partly because of the communication from eyes to brain to fingers. Although the nerves transmit very quickly, the transmission time can still take a little while.

There are two separate systems at work here: the central nervous system is your brain and spinal column and the longer nerves branching out from the spinal cord to every part of your body is the peripheral nervous system. They work in conjunction to coordinate your actions.

If you lines up all of your nerves, end to end, they would stretch for miles and miles: an average length is about 47 miles of nerves. The longest is the sciatic nerve. It goes from the bottom of your spine to the bottom of your foot.

Exercises

What is the voluntary response in this experiment?
What is an involuntary response in your body? Give an example.

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Camera Eyes

Tuesday November 15, 2011

Your eyes have two different light receptors located on the back of the eyeball. These are the rods, which see black, white and grays, and the cones, which see color. In order to adapt to the dark, our eyes make a chemical called visual purple. This helps the rods to see and transmit what you see in situations where there is little light.

Your pupils also increase in diameter in the darkness. This allows for a slight increase in the amount of light entering your eye. This combination of visual purple and more light makes it possible for you to see in darker situations.

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Here’s what you need

- 1 dark room
- 1 light switch
- 1 partner
- 1 pencil

Download Student Worksheet & Exercises

Here’s what you do

Turn out the light in a darkened room and give your eyes about 5 minutes to get used to the darkness.
After your eyes have had a chance to acclimate to the low-light conditions, it’s time to get to work. Try to draw a picture of your assistant’s eye. Pay particular attention to how the pupil looks in the darkness.
Now turn on the light while still observing your partner’s eye. What happens to their pupil?
Draw another picture of your partner’s eye with the lights on. Again, pay special attention to the pupil.

What’s going on?

As you flip the light switch on, your partner’s brain realizes that there is a lot of light entering the rods and cones, so it restricts the size of the opening (your partner’s pupil) in order to limit the light. You might notice this on a sunny day if you go from a dark movie theater into the bright sun. It can actually hurt for moment, and makes you squint until your eyes have a chance to adjust to the brightness by reducing the size of your pupils.

Exercises

How does the pupil adapt to light conditions?
What are the two special photoreceptors called and where are they located?
Which photoreceptor is used to help us see in the dark?

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Human Levers

Monday November 14, 2011

Levers are classified into three types: first class, second class, or third class. Their class is identified by the location of the load, the force moving the load, and the fulcrum. In this activity, you will learn about the types of levers and then use your body to make each type.

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Here’s what you need

- 1 body

Download Student Worksheet & Exercises

Here’s what you do

In a first class lever, the fulcrum is in the middle. The load and effort are on opposite sides with the fulcrum between them. A familiar example of a first class lever is a see saw.
A second class lever has the fulcrum on one end, the load in the middle, and the force on the end opposite the fulcrum. A wheelbarrow is a good example of a second class lever.
Lastly, a third class lever has a fulcrum on one end and the load on the opposite end. The force is applied in the middle in this type of lever. A golf club is an example of a third class lever.
Use the photos to identify the levers of each type in your body.

What’s going on?

Only read further if you have had an opportunity to identify the levers in the pictures. Spoilers below!

Your head moving up and down on your spine is an example of a first class lever. Your neck joint in the middle is the fulcrum, with load and effort on either side. In this example, load and effort switch depending on whether you are moving your head up or down.

Standing on tiptoe is an example of a second class lever where your toes are the fulcrum. The effort, or force, is in your heels – they are lifting your body up. And the resistance is located between your toes and heels.

This leaves us with bicep curls, which are an example of a third class lever. Your elbow serves as the fulcrum, the bicep is the force, and the weight in your hand on the end is the load.

Just for fun, did you know your knee is the largest joint in your whole body? It connects your femur, the largest bone, to the bones of your lower leg. Your smallest joints are the anvil, hammer, and stirrup in your inner ear.

Exercises

Draw a diagram of a first-class lever. Where in your body is this type of lever?
Draw a diagram of a third-class lever. Where will you find this?
Draw a diagram of a second-class lever. Can you give an example of this type of lever in the real world?

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Sound Speed

Monday November 14, 2011

Sound has the ability to travel through the states of matter: solids, liquids, and gases. In this experiment we will study the movement of sound through these three states.

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Here’s what you need

- 3 baggies, resealable
- sand
- water
- air
- 1 desktop
- 1 spoon
- 1 partner

Download Student Worksheet & Exercises

Here’s what you do

Fill each bag two-thirds of the way full with each material. You should have one bag with sand, one with water, and one with air. Seal each baggie well.
Put the baggies on the desk or on a table. Note the density of the materials. Which is most dense, medium, and least dense?
Place your ear down on the first baggie that is filled with sand. Have your partner use the spoon to tap the table. Listen for the sound through the bag of sand.
Repeat step 3 with the baggie full of water and then the bag of air. Compare what you hear through each state of matter. Rank the tapping you hear through the solid, liquid and gas in order from loudest, to medium, to quietest.
When you have completed the tapping portion of the experiment, hold the bag of sand up to your ear. Have your partner speak to you through the baggie.
Repeat step 5 with the bag of water and again with the baggie of air. Note the clarity of the speech you hear through each bag. Rank each bag from loudest, to medium, to quietest.

What’s going on?

Sound is made by waves travelling through the air. They pass their energy along to the matter through which they are traveling. But now you know that sound doesn’t just travel through the air. Molecules in water are closer together than air molecules, which makes it much easier for them to bump into one another. So the speed that sounds travel through liquid is actually faster than it travels through the air, and the sounds travel further as well. Sound travels fastest of all in solids because the molecules in this state of matter are very densely packed together. Solids pass sound much farther and at much greater speeds.

If there is no matter to bounce their energy along, sound waves can’t really form. So once you leave earth’s atmosphere, there isn’t any sound!

Exercises

What is density?
Put these in their general order of density: liquid, gas, solid.
Which material passes sound waves along farther and faster?

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Sound Matching

Monday November 14, 2011

You know that sound comes from vibration which are picked up by the pinna (external part of the ears). Then the vibrations vibrate your tympanic membrane, which in turn vibrates the ossicles and then the cochlea. The cochlea sends information through the auditory nerve and sends it to the brain, which recognizes it as sound.

In this lab, you will testing your ability to sort and match different sounds.

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Here’s what you need

- 10 film canisters (for 53 mm film rolls)
- beans
- rice
- sawdust (or pencil shavings)
- paperclips
- pennies
- 1 black, felt marker
- assistant

Download Student Worksheet & Exercises

Here’s what you do

Take the caps off the canisters. Number half of them 1 to 5 and mark the others with A through E.
Prepare your experiment while your partner is out of the room. Fill five of the numbered containers with one of the materials. Note which canister contains each material for data records.
Next fill the lettered containers. Be sure to record which container contains which material for reference.
When the contents have been noted and the lids all replaced, bring in your partner into the room. Ask them to match the sound of the item in the first canister with one of the lettered containers. They can shake, roll, and even drop the containers, but they can’t take off the lid. Note the answer they give.
Repeat step 4 for the rest of the numbered containers. Remember to record the responses. When the canisters have all been matched, take off the lids and see how well they did.

What’s going on?

Objects produce distinct sounds when they vibrate. These differences can sometimes be distinguished by your ears. If you partner has good ears, listening closely and then correctly matching the contents was probably an easy task.

Now to share a little more about the cochlea: you know it ultimately receives sounds and sends signals to the brain. It is a small organ shaped like a spiral. It’s filled with fluid and tiny cells which are shaped like hairs. These hairlike cells convert the vibrations from sound into signals that can travel the auditory nerve up to the brain. The tiny cells are quite sensitive. They can actually be damaged by extremely loud noises, so remember to protect them with earplugs if you will be exposed to very loud sounds.

Exercises

What are the tiny bones in the ear called?
Name some other parts of the ear.

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Sound Whackers

Monday November 14, 2011

Have you ever held a plastic ruler over the edge of a desk or table and whacked the end of it? If so, you would notice a funny sound. This sound changes if you change the length of the ruler that is hanging over the edge. The sound you hear is made by the ruler’s vibrations.

In this lab, we begin to learn about sound. You know it is collected and deciphered by your ears, but did you also know that all sound is made when something vibrates? It could be a guitar string, vocal chords in your throat, or a plastic ruler that is hanging over the edge of the desk: vibrations make sound.

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Here’s what you need

1 desk
1 metric ruler

Download Student Worksheet & Exercises

Here’s what you do

Place the ruler on the desk at the 20 centimeter mark. Hold the portion of the ruler that’s still on the desk down very firmly with one hand. Press down the portion of the ruler hanging off the desk with the other hand. Now let it go. The ruler should begin to vibrate up and down while producing a strange sound.
Now rearrange the ruler so that it is placed at the 15 centimeter mark and give it a thump. What happens to the pitch this time? Is it higher or lower now that the overhanging portion is shorter?
Make sure you try the ruler at 5 centimeters, 10 centimeters, 15 centimeters, 20 centimeters, and 25 centimeters. Listen each time and place the lengths in order from highest to lowest pitch.
Finally, put the ruler at the 25 centimeter mark, with just 5 centimeters on the table and the rest hanging over the edge. Give it a whack and while it’s vibrating, slide the ruler back across the edge of the table to make the overhanging portion shorter and shorter. What happens to the sound?

What’s going on?

The overhanging portion of the ruler is the portion allowed to vibrate. This determines the sound’s pitch. When a short piece is hanging over the edge, a high pitch is made. And when the length is longer, the pitch is lower. This is what happens with all vibrating objects and is a function of their wavelengths.

Did you know that the tiniest bones in your body are found in your ear? They are called ossicles and include the hammer, anvil, and stirrup. They are located just behind your eardrum and collect the vibrations that come into the ear canal and hit your ear drum. When your ear drum begins to vibrate, the tiny bones vibrate as well. This causes your cochlea to vibrate as well, and it sends a signal to your brain for it to interpret.

Exercises

How is sound made?
How do you change the pitch of the ruler?

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Big Ears

Monday November 14, 2011

How do you think animals know we’re around long before they see us? Sure, most have a powerful sense of smell, but they can also hear us first. In this activity, we are going to simulate enhanced tympanic membranes (or ear drums) by attaching styrofoam cups to your ears. This will increase the number of sound waves your ears are able to capture.

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Here’s what you need

- 2 styrofoam cups, 12 oz.
- 2 styrofoam cups, 32 oz.
- 1 pair of scissors
- 1 kitchen timer

Download Student Worksheet & Exercises

Here’s what you do

Set the timer and put it on a table or desk. Walk about 6 feet away and face the timer. Listen for the ticking sound. Now, turn your back on the clock so that you are facing the other direction. How has your ability to hear the ticking changed? We can increase the sounds you hear by using the cups.
Get an adult to help with cutting the cups. They will hold one of the smaller cups with one hand and make a cut about an inch (3 cm) from the rim toward the bottom of the cup.
Draw a circle at the end of the cut that is about the size of your ear where it attaches to your hear. Cut out the circle.
Repeat steps 2 and 3 with the other 12 oz. cup. Carefully put them on your ears with their openings pointing forward. You have just added to the size of your ears and they should be able to collect more sound vibrations. Try listening to the timer now with the cups on your ears.
Now repeat steps 2 through 4 with the larger cups. Set the timer one more time and listen to the timer. Compare what you hear with what you heard with your unenhanced ears, and what you hear with the 12 oz. ears.
On a scale of 0-10, how much did the cups improve what you were able to hear? Note where you would place both the 12 oz. cups and the 32 oz. cups on the scale if 0 is the starting point equal to what you can hear with your own ears.
Repeat step 5 with the bag of water and again with the baggie of air. Note the clarity of the speech you hear through each bag. Rank each bag from loudest, to medium, to quietest.

What’s going on?

Hearing is based on movement. The initial process involves the actual waves coming toward your ear, which are funneled inside to your tympanic membrane.

In this experiment we focused on the initial funneling process. This is done by the visible, external part of your ear, known as the pinna. By making the pinna larger, you also increased their ability to pick up sound vibrations. This enabled you to hear much more, and at louder levels.

The pinna also help to determine the direction from which sound is coming. If a sound is coming from the left, your left ear hears it a little bit before the right. This lets your brain know where the sound originates.

Exercises

Which part of the ear is this experiment testing?
What happens when you change your variable in this experiment?
Did this experiment change your ability to detect which direction a sound came from?

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Testing Muscle Strength

Sunday November 13, 2011

Some groups of muscles are stronger than others because each group is designed for a different and specific function. It just makes sense that the muscle groups in our legs would need to be stronger than the ones in our toes.

For this experiment, you will use a bathroom scale to test the strength of various muscle groups.

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Here’s what you need

1 bathroom scale
1 pencil
1 partner

Download Student Worksheet & Exercises

Here’s what you do

Put the scale between your knees. Now squeeze it as hard as you can and have your partner record the scale’s reading.
Use the technique to test the muscles in the following list. Place the scale between the body parts and squeeze! Be sure to record the readings for data-keeping purposes.

a. thighs

b. ankles

c. palms

d. elbows

e. elbow and rib cage

What’s going on?

Not all muscles need to be big and powerful. Actually, muscles have various functions and uses that vary by their design. The muscles in our fingers are detail-oriented. They need to be fast and perform relatively small, precise movements like the ones used in writing. The design of a specific muscle group will vary depending upon the muscles’ ultimate use.

Have you even had a muscle cramp? They occur when a muscle is overworked and fatigued. The muscle simply contracts and stays contracted. Not fun!

Exercises

What are the two main types of muscles?
Give an example of a muscle group that’s more specific than your answers above.
Why aren’t the muscles in our fingers big and strong like those in our arms and legs?

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Inside Bones

Sunday November 13, 2011

The skeleton is your body’s internal supporting structure. It holds everything together. In addition to providing support, bones act as shock absorbers when you jump, fall, and run. Bones have big responsibilities and so they must be really strong. They also need to be arranged properly for the best support and shock absorption.

In this experiment, we will look at the internal arrangement of the bones holding together your body.

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Here’s what you need

1 toilet paper tube
50-100 straws
1 roll of tape
1 book

Download Student Worksheet & Exercises

Here’s what you do

First you will explore different bone structures. Start by taking 20 skinny straws and arrange them randomly in your hand so that they are pointing in different directions.
Lay your arm and hand on a table so that it is braced. Next, have a friend place a heavy book on this column of straws. What happens then it’s exposed to the weight?
Now take 20 more straws and arrange in a circle so that they are all held vertically in your hand.
Repeat step 2 with these more organized straws. Do you notice a difference? The uniformly arranged straws should be stronger than those that were randomly arranged.
The tubes inside your bones are more like the uniform model of straws. They also have a kind of glue that hold them in place inside the bones. Let’s incorporate this idea into your model by lining the inside of the toilet paper tube with tape.
Next, add some straws inside the tube as well. Add a single layer of straws, then another layer on top of it. Finally, fill the middle of the tube with straws, making sure they are tightly packed.
Test your model’s strength by placing a book on top of the tube. What happens when the model is exposed to the book’s weight?
For an extra study opportunity, visit the butcher in your local grocery store and ask for the end of a beef bone. (This is sometimes packaged as a soup bone). Look at the end of the bone. What do you see? It should look like a hard outer shell of bone protecting a softer, spongy portion. Draw a picture of your observations.

What’s going on?

In your experiment, it should have been readily apparent that the more organized and uniform straws were much stronger than the randomly arranged ones. Your own bones have a similar pattern in their soft, spongy part called cancellous bone. This portion of bone has a honeycombed structure which makes the bones very strong, but relatively light. The tiny tubes that make up the honeycomb are called the Haversian system and the actual tissue of the structures is made up of collagen. This allows them to maintain flexibility, but they are still composed of minerals – notably calcium and phosphorus which give them their hardness and strength.

Exercises

Name some of the parts that make up our skeletal system.
What is the smooth, hard, protective layer on the outside of bones called?
What is the inside spongy, porous, honeycombed bone called?
What is the network of tubes inside bones called?

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Nerve Tester

Sunday November 13, 2011

Our sense of touch provides us with information that helps us to process and explore our world. Nerves play an important part in the sense of touch by being the wires that carry signals from the skin to the brain. But the body has a plan in place so that our brains don’t get overwhelmed with too much information. This plan is a lot like a blueprint for wiring a house. Just like a house has light switches and electrical outlets in strategic locations, our bodies have touch receptors of various numbers based on their location. In this lab, we will explore an arm to determine where the highest concentrations of nerves are in that limb.

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Here’s what you need

- 1 large paper clip
- 1 metric ruler
- 1 partner

Download Student Worksheet & Exercises

Here’s what you do

Unfold a paperclip so that it has two open ends. The ends should be about a centimeter apart.
Have your partner uncover their arm up to the shoulder. They should place this arm on the table, palm up, but it is also important that they face away from you. They shouldn’t be able to see the test.
GENTLY touch one or both of the open paperclip ends to your partner’s fingertip. Ask your partner to determine how many points you used to touch them (one or two). Then record their response as (Y) for a correct answer or (N) for incorrect.
Continue testing based on the numbered points in the diagram. Randomly vary the points used to touch your subject’s skin, recording their Y (correct) or N (incorrect) response for each individual area.
Repeat steps 3 and 4, with the paperclip ends separated at a distance of 3 cm, 5 cm, and 10 cm.
Your turn! Switch places and have your partner test you and record your responses.
Finally, use the diagram and your data to design a map of nerve concentrations in the arm and hand. What are some of the advantages of this nerve placement?

What’s going on?

Endings are nerves are located so that we can use them to collect data. The highest concentrations of nerves are in our hands, feet and mouths. We use our hands to gather a lot of data, our feet for moving around, and our mouths for speaking. Luckily, the areas of our bodies that are more likely to be bumped and the ones we use to help protect ourselves have fewer nerve endings. Areas of particularly low concentration include our backs, rear ends, and arms.

Our tongues have the highest nerve concentration of all. In fact, nerve mapping researchers have learned that over half of our brain’s sensory nerves are connected to our tongues. It makes sense when you realize that we taste, talk, and feel with this relatively small organ. It really needs to connect to so many places in the brain!

Exercises

Where is the highest concentration of nerve endings in the body?
What are nerve ends used for?
Where do you think the least amount of nerve ends should be in the body?

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Tendon Reflex

Saturday November 12, 2011

Involuntary responses are ones that you can’t control, but they are usually in place to help with survival. One good example is when you touch something hot. Your hand does not take the time to send a message to your brain and then have the brain tell your hand to pull away. By then, your hand might be seriously hurt! Instead, your body immediately removes your hand in order to protect it from further harm.

Today you will test an involuntary reflex by using the tendon reflex test. A thick, rubbery band called the patellar tendon holds your knee cap in place. Having one leg on top of the other not only stretches the tendon, but it also makes it possible to see a reaction. You can test the reflex by giving your tendon a tap and watching what happens.

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Here’s what you need

1 knee
1 partner

Download Student Worksheet & Exercises

Here’s what you do

Sit with your legs crossed at the knee on the edge of your seat. Reach forward and see if you can feel the patellar tendon. It is right below your knee cap.
Ask your partner to gently tap the tendon with the outside edge of their hand. This will look like a careful little karate chop. If your partner gets the right spot it will be obvious. You will notice your leg kick out a little in a reflex reaction.
Your partner can try other spots on the tendon if reaction isn’t achieved at first. If it hurts, stop right away! It’s possible that you might not have a tendon response reflex. Not everyone does and that is perfectly normal.

What’s going on?

There are three main parts that make up your peripheral nervous system. They are the autonomic nerves, which control reflexes like the one we have studies here. Autonomic nerves also send information to your organs, blood, and other parts of the body. The second part of your peripheral nervous system is made up of the nerves that deal with the five senses. The last part is your motor nerves. They help you to move the muscles in your body and are responsible for voluntary reactions.

The tendon reflex is in place because the knee is such a sensitive and vulnerable part of the body. When the tendon is stretched out and bumped, your body tries to move the leg and knee out of harm’s way so that it won’t get hurt. As you could probably tell, it’s an involuntary response that neutralizes any conscious, voluntary control that your brain has over the leg through the motor nerves.

Exercises

What are the main parts of the nervous system?
What are the two parts of the peripheral nervous system and what are their functions?
Which part of the nervous system controls involuntary reflexes?

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Detecting Plaque

Thursday November 10, 2011

The buildup of things like food and bacteria where your gums and teeth meet, and also between your teeth, is called plaque. Where plaque lives is also where the bacteria turns the sugar in your mouth into harmful acids that attack your teeth’s enamel and can lead to gum disease. Regular brushing is a great way to remove plaque and keep your mouth healthy.

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Here’s what you need

1 4-pack of red disclosing tablets
1 clear plastic cup
1 mirror
1 red crayon
water

Download Student Worksheet & Exercises

Here’s what you do

Disclosing tablets are designed to identify plaque by turning it red. Remove a pill from the packaging and put it in your mouth. Chew it up thoroughly but don’t swallow it. Be very careful not to get any of the dye on clothing or anything else that might stain. The color is very difficult to remove!
Take the cup full of water and rinse out your mouth very well. Spit the water out into the sink. Check your mouth in the mirror. All of that red is plaque! Draw a picture of your mouth and use the red crayon to note where the plaque is attacking your teeth and gums.
You should have a total of 4 pills in the package. You can test other members of your family, or if you would prefer, test yourself over a period of a few days after you have had a chance to observe and identify where you should be doing a better job of tooth-brushing.

What’s going on?

When you chew the tablets they start to dissolve and mix with your saliva. This makes a water soluble dye that affixes to the bacteria and other particles in your mouth. The dye is absorbed by the bacteria, so it holds onto it even after your mouth is rinsed. This enables you to identify the unbrushed areas in your mouth.

Have you ever counted your teeth? They started to appear when you were a baby – about 6 months old or so. Kids have 20 deciduous, or baby teeth. These will fall out and the adult teeth grow in to replace them. Adults usually have 32 total teeth.

Exercises

Why does this experiment work at detecting plaque?
How can dentists and moms use this to make sure you’re doing a good job brushing?
What is plaque, and why is it bad for you?

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How Much Energy Does the Sun Produce?

Friday November 4, 2011

Without the sun, there would be no life on Earth. The sun warms the earth, generates wind, and carries water into the air to produce rain and snow. The energy of the sun provides sunlight for all the plant life on our planet, and through plants provides energy for all animals.

The sun is like a giant furnace in which hydrogen nuclei (atoms without electrons) are constantly smashed together to form helium nuclei. This process is called nuclear fusion. In this process, 3.6 billion kilograms (8 billion pounds) of matter are converted to pure energy every second. The temperature in the sun exceeds 15 million degrees.

Nuclear fusion is one kind of energy. Other forms of energy include: mechanical energy, heat, electrical energy, chemical energy, and light. Mechanical energy is the energy of organized motion, such as a turning wheel. Heat is the energy of random motion, such as a cup of hot water. Electrical energy is the energy of moving charged particles or electrons, such as a current in a wire. Chemical energy is the energy stored in bonds that hold atoms together. Light is any form of electromagnetic waves, such as X rays, microwaves, radio waves, ultraviolet light, or visible light.

Energy can be converted from one from to another. For example, the nuclear energy of the sun is converted to light, which goes through space to the earth. Solar collectors of mirrors can be used to focus some of that light to heat water to steam. This steam can be used to turn a turbine, which can power a generator to produce electricity.

Most of our energy needs are met by burning fossil fuels such as coal, oil, gasoline, and natural gas. The chemical energy stored in these substances is released by burning these fuels. When fossil fuels burn, they combine with oxygen in the air and produce heat and light.

Fossil fuels are not renewable. When they are used up, they are gone forever. However, renewable energy sources such as wind, sun, geothermal, biomass and water power are renewable. They can be used over and over to generate the energy to run our society.

Tremendous amounts of renewable energy are available. For example, the solar energy that falls on just the road surfaces in the United States is equal to the entire energy needs of the country. Although there are sufficient amounts of renewable energy, we must improve our methods of collecting, concentrating, and converting renewable energy into useful forms.

In the following experiments, you will learn something about the amount of energy the sun produces at the earth’s surface and how heat energy can be stored.
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Materials

Water
Disposable, aluminum pie pan
Paint brush
Measuring cups
Watch or clock
Newspaper
Black paint or spray paint (flat, not shiny)

Procedure

Go outside and spread out a sheet of newspaper. Place an aluminum pie pan on the newspaper. Carefully bend one spot on the edge of the pie pan to make a spout shape. This will allow you to more easily pour water out of the pan. Have an adult help you paint the inside of the aluminum pie pan. You can use a brush and a can of paint or spray paint. Be sure not to get the paint on anything except the disposable pie pan and the newspaper. After painting, set the pie pan where the paint can dry overnight.

You will need to do the rest of this experiment on a warm, sunny day. You do not want the pie pan to be in the shade. Set the aluminum pie pan in a warm, sunny spot. The sun will need to constantly shine on the pie pan. The black color of the pie pan allows it to absorb, rather than reflect, solar energy. You will need to begin the experiment about

11:00 A.M., so the solar heating will be done when the sun is high in the sky.

Add exactly one cup of water to the pie pan. Wait four hours while the sun is shining on the pan of water. After exactly four hours of sunshine, carefully pour the remaining water from the pie pan into a one-half or one-fourth measuring cup. Use these measuring cups to estimate the amount of remaining water to the nearest one-eighth of a cup.

Observations

Is the amount of water in the pie pan less than when you began the experiment? How much water is left in the pie pan after four hours of sunlight?

Discussion

You will probably observe that the amount of water in the pie pan is less after four hours of sunlight exposure. Where did the water go? As the sunlight shines on the dark surface of the painted pie pan, solar energy is absorbed and heats the pan and the water. This energy causes a portion of the water to evaporate. As water evaporates, it leaves the liquid form and goes into the air as a gas (water vapor). You will probably find that some, but not all, of the water evaporated.

Scientists use the unit of joule as a measure of energy. However, you may find it helpful to think in units of dietary calories instead of joules. One dietary calorie is equal to 4,184 joules of energy. One cup of breakfast cereal with one-half cup of milk would have about 240 dietary calories, or approximately 1,000,000 joules of energy. Although the earth receives only a tiny portion of the total energy output of the sun, the earth has a constant supply of 173 million billion (173,000,000,000,000,000) watts of solar power. A watt is a unit of power equal to a joule of energy used per second. For comparison, a typical light bulb to run a lamp in your home might require 100 watts of power. A million watts could supply the energy needs of about 500 average American homes.

Use the table below to determine the solar energy required to evaporate a certain amount of water. The amount of water remaining in the pan will allow you to determine how much energy was used, how much power was used, and the amount of power per area.

Your results will probably be in the middle range of this table. For example, if one-half of your water evaporated, then the water remaining would be one-half cup. Thus, the energy used to evaporate this water would be 289,000 joules of energy. This energy would give a power of 20 watts, and a power per area of 800 watts per square meter (watts / meter²).

Solar Energy Required to Evaporate Water
Water Remaining (cup)	Water Evaporated (cup)	Energy Used (joules)	Power Used (watts)	Power per Area (watts / meter²⁾
1	0	0	0	0
7/8	1/8	72,250	5	200
3/4	1/4	144,500	10	400
5/8	3/8	216,750	15	600
1/2	1/2	289,000	20	800
3/8	5/8	361,250	25	1000
1/4	3/4	433,500	30	1200
1/8	7/8	505,750	35	1400
0	1	578,000	40	1600

The following procedure was used to generate the numbers in the Table. It is known that it takes 578,000 joules of energy to evaporate one cup of water. This known energy per cup is multiplied by the fraction of a cup that was evaporated. This gives the solar energy used to evaporate the water in the pie pan. The energy is divided by the number of seconds in four hours (14,400 seconds). This gives the power of the solar energy striking the pie pan, since a watt is equal to a joule per second. Finally, the power (in watts) is divided by the surface area of the pie pan (0.025 square meters) to give the power per area.

When the sun is overhead, the intensity of solar energy can be as much as 1,000 watts per square meter. If all of this energy could be converted to electricity, one square meter of sunshine would be enough to run ten 100-watt light bulbs. However, our current solar cells that convert sunlight to electricity are able to change only about 15 percent of the light to electricity.

You can see from this experiment that there is tremendous energy available from our sun. Most of this energy warms our planet or is reflected back into space. Among other things, the remaining portion of energy powers our water cycle, producing rain and snow, or provides plants with the energy they need to live.

Scientists and engineers are learning more about trapping solar energy and converting it to useful power. It has been estimated that all forms of potentially available renewable energy (wind, water, biomass, and direct solar) have an energy equivalent to 80 trillion barrels of oil. In other words, one year of renewable solar energy is 5,000 times greater than the current yearly energy needs of the United States. In comparison, it has been estimated that all the remaining coal, oil, natural gas, and other potential nonrenewable energy reserves of the United States are equal to about 8 trillion barrels of oil.

Since we do not yet know how to use a significant portion of this renewable energy, much work remains to be done. In the remainder of this book you will learn more about our current ability to use renewable energy and the promise it may hold for the future.

Other Things to Try

Repeat this experiment using different amounts of water on different days and compare the solar power you find.

Repeat this experiment in the late afternoon, when the sun is lower in the sky. How do your result compare to this experiment?
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How Can Water Be Used to Store Heat Energy?

Friday November 4, 2011

Temperature is a measure of the average hotness of an object. The hotter an object, the higher its temperature. As the temperature is raised, the atoms and molecules in an object move faster. The molecules in hot water move faster than the molecules in cold water. Remember that the heat energy stored in an object depends on both the temperature and the amount of the substance. A smaller amount of water will have less heat energy than a larger amount of water at the same temperature.

Increasing the temperature of a large body of water is one way to store heat energy for later use. A large container filled with salt water, called brine, may be used to absorb heat energy during the day when it is warm. This energy will be held in the salt water until the night when it is cooler. This stored heat energy can be released at night to warm a house or building. This is one way to store the sun’s heat energy until it is needed.

Solar ponds are used to store energy from the sun. Temperatures close to 100°C (212°F) have been achieved in solar ponds. Solar ponds contain a layer of fresh water above a layer of salt water. Because the salt water is heavier, it remains at the bottom of the pond-even as it gets quite hot. A black plastic bottom helps absorb solar energy from sunlight. The water on top serves to insulate and trap the heat in the pond.

In a fresh water pond, as the water on the bottom is heated from sunlight, the hot water becomes lighter and rises to the top of the pond. This convection or movement of hot water to the top tends to carry away excess heat. However, in a salt water pond, there is no convection so heat is trapped. In Israel a series of salt water, solar ponds were developed around the Dead Sea. The heat stored in these solar ponds has been used to run turbines and generate electricity.
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Materials

Two paper cups
Measuring cups
Hot water
Watch or clock
Sink
Refrigerator (with freezer compartment)

Download Student Worksheet & Exercises

Procedure

Turn on the hot water faucet of a sink and wait several minutes until the water is hot. Be careful not to burn yourself with this hot water. Add one-fourth cup of this hot water to the first paper cup. Add one cup of hot water to the second paper cup. Place both of these cups in the freezer compartment of a refrigerator.

After thirty minutes check the water in each cup. Return the cups to the freezer compartment and check them again after fifteen minutes. Keep checking the cups each fifteen minutes until the water in one of the cups is frozen.

Observations

Does the water in the cups freeze at the same time? Does the water in one of the cups freeze first? How long does it take for the water to freeze?

Discussion

You will probably observe that the smaller amount of water in the first cup freezes prior to the larger amount of water in the second cup. Both cups were filled with the same hot water. However, even though the water in both cups was at the same temperature, they did not freeze at the same time. The amount of heat energy stored by the water depends on both the temperature and the amount of water.

We expect that the more heat energy stored in the cup, the longer it takes the water in the cup to freeze. Since one cup of water has more heat energy than one-fourth cup of water, it takes the larger amount of water longer to freeze.

Other Things to Try

Place one-half cup of hot tap water in one cup. Place one-half cup of cool tap water in a second cup. Put both cups in the freezer compartment of a refrigerator and check them every fifteen minutes until the water freezes solid. Which cup of water do you think has more heat energy? Which cup of water do you think will freeze first?

Place one cup of water in one paper cup and one-fourth cup of water in a second paper cup. Put both cups in the freezer of a refrigerator and leave overnight. The next day remove both cups of frozen water. Set the two cups out in the room. Observe the time it takes each piece of ice to melt. Which piece of ice do you think will melt first? Which piece will require more heat energy to cause it to melt?

Exercises

What type of heat transfer is at work in a solar pond?
1. Kinetic
2. Conduction
3. Potential
4. Convection
5. Radiation
What units do we use to measure energy?
1. Kilowatts
2. Joules
3. Newtons
4. Kilowatt-hours
Draw a diagram of a solar pond in the space below:

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Can Wind Be Used as a Source of Energy?

Friday November 4, 2011

The United States has large reserves of coal, natural gas, and crude oil which is used to make gasoline. However, the United States uses the energy of millions of barrels of crude oil every day, and it must import about half its crude oil from other countries.

Burning fossil fuels (oil, coal, gasoline, and natural gas) produces carbon dioxide gas. Carbon dioxide is one of the main greenhouse gases that may contribute to global warming. In addition, burning coal and gasoline can produce pollution molecules that contribute to smog and acid rain.

Using renewable energy-such as solar, wind, water, biomass, and geothermal-could help reduce pollution, prevent global warming, and decrease acid rain. Nuclear energy also has these advantages, but it requires storing radioactive wastes generated by nuclear power plants. Currently, renewable energy produces only a small part of the energy needs of the

United States. However, as technology improves, renewable energy should become less expensive and more common.

Hydropower (water power) is the least expensive way to produce I electricity. The sun causes water to evaporate. The evaporated water falls to the earth as rain or snow and fills lakes. Hydropower uses water stored in lakes behind dams. As water flows through a dam, the falling water turns turbines that run generators to produce electricity.

Currently, geothermal energy (heat inside the earth), biomass (energy from plants), solar energy (light from concentrated sunlight), and wind are being used to generate electricity. For example, in California there are more than sixteen thousand (16,000) wind turbines that generate enough power to supply a city the size of San Francisco with electricity.

In addition to producing more energy, we can also help meet our energy needs through conservation. Conservation means using less energy and using it more efficiently.

In the following experiments, you will use wind to do work, examine how batteries can store energy, and see how insulation can save energy.
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Materials

Pinwheel (can be purchased or madefrom construction paper)
Paper clips
Tape
Small shoe box (children’s size)
Electric fan
Lightweight string (about 4 feet long)
Plastic straw (longer than the width of the shoe box)
Hole punch

Download Student Worksheet & Exercises

Procedure

In this activity, you will try to use the energy in the wind to lift a set of six paper clips. You will first need to construct your windmill.

Use a hole punch to punch holes in the opposite sides across the width of a small, cardboard shoe box. Use the narrow sides of the box so the two holes are less than six inches (15 centimeters) apart. Make sure the holes are directly opposite each other. Place a plastic straw through the two holes. You may need to use the hole punch to enlarge the holes so the straw can rotate within the holes. The ends of the straw should extend out either side of the box.

Use the blades from a purchased pinwheel, or cut and fold a square piece of construction paper into the shape of a pinwheel. Next you will need to attach the pinwheel blades to one end of the straw. Partially unfold a small paper clip and insert the larger end into the straw. Push the straightened end of the paper clip through the center of the pinwheel. Bend this end of the paper clip and tape it to the outside of the pinwheel.

Set the electric fan on a table or countertop. Hold the shoe box so that the pinwheel is free to turn. HAVE AN ADULT PLUG IN AND TURN ON THE FAN. Move the windmill box to direct the breeze from the fan toward the blades of the pinwheel. Move the box until you find the best angle of the fan to the pinwheel so that the pinwheel turns freely and rapidly.

Turn off the fan. Now tape one end of the string to the side of the straw with no pinwheel just outside the box, and wrap the string around the straw a few times. Tie the other end of the string to a paper clip. Attach five other paper clips to the paper clip tied to the string. Allow the string to hang down so that the paper clips on the end of the string rest on the floor.

Now, you will test to see if your windmill can convert wind power to do work and lift the paper clips off the ground. Turn on the fan and hold the box where you did before to make the pinwheel turn.

Observations

Does the windmill turn the straw? Does the string wrap around the straw as the straw turns? What happens to the paper clips?

Discussion

You should observe the straw shaft turning as the wind from the fan is directed toward the blades of the pinwheel. As the pinwheel turns, it should wrap the string around the straw and lift the paper clips into the air. Your windmill converts the energy of the wind to work and lifts the weight of the paper clips. If your windmill is not working, then examine all the parts.

Compare your setup to the drawing, and see if any changes need to be made in your construction.

One way to store the energy produced by a windmill is to lift a weight. When the weight is allowed to fall, work can be produced. Weights in a grandfather clock are used to store energy and can run a clock for a week or longer. A windmill’s energy can be used to pump water to a storage area at a higher elevation. Later, this water can be allowed to fall through a turbine which turns a generator and produces electricity.

Electricity can also be produced directly from wind power. The shaft, or rod to which the windmill blades are attached, can be used to turn a generator. A generator or dynamo is used to convert mechanical energy into electrical energy. Power conversion units can change the direct current that wind generates to an alternating current. The alternating current can be fed directly into utility lines and used in our homes.

The sun is the original source of wind power. Without the sun to heat the earth, there would be no wind. The energy of the sun heats the earth, but all parts of the earth are not at the same temperature. These differences in temperature are responsible for global and local patterns of wind. For example, during the day a constant wind blows from the sea toward the land along coastal regions. Air above the hotter land rises and cooler, heavier air above the ocean moves in to take its place.

The power of the wind can be harnessed to do work. For at least 4,000 years, the wind has been used to move sailing ships. The wind has enough power to move ships across oceans and around the world.

For at least 1,000 years, windmills have been used for pumping water and turning

stones to grind grain. Millions of windmills have been used on the plains of America, Africa, and Australia to pump water from deep wells for livestock and humans.

In this century, windmills or wind engines have been used to generate electricity. Over 15,000 wind engines were installed in California in the 1980s. These wind engines have the capability to produce up to 1.5 billion watts of electricity. In California in 1987, wind was used to produce as much electricity as the city of San Francisco uses in an entire year.

Other Things to Try

Repeat this experiment and find the maximum weight you can lift with your windmill. Try more paper clips or try a heavier weight such as a pen.

List some of the problems associated with using windmills. What happens when the wind is blowing too gently? What happens if the wind blows strongly, such as in a storm? Do you think the area where you live is windy enough for wind engines to produce electricity?

Exercises

Name three sources of renewable energy:
What does the sun have to do with wind?
Name three examples of wind power in historical or current usage:

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Can a Battery Be Used to Store Energy?

Friday November 4, 2011

A battery is a device that produces electrical energy from a chemical reaction. Another name for a battery is voltaic cell. Voltaic means to make electricity.

Most batteries contain two or more different chemical substances. The different chemical substances are usually separated from each other by a barrier. One side of the barrier is the positive terminal of the battery and the other side of the barrier is the negative terminal. When the positive and negative terminals of a battery are connected to a circuit, a chemical reaction takes place between the two different chemical substances that produces a flow of electrons (electricity).

When a battery is producing electricity, one of the chemical substances in the battery loses electrons. These electrons are then gained by the other chemical substance.

A battery is designed so that the electrons lost by one chemical substance are made to flow through a circuit, such as a flashlight lamp, before being gained by the other chemical substance. A battery will produce a flow of electrons until all of the chemical substances involved in the chemical reaction are completely used.

[am4show have='p8;p9;p22;p49;p75;p84;p58;' guest_error='Guest error message' user_error='User error message' ]

Materials

Earphone or headset for a portable radio
Small piece of aluminum foil
Tomato paste or tomato ketchup
New, shiny penny
Two wires with alligator clips on each end of the wires
Plate
AA-size battery
Spoon

Download Student Worksheet & Exercises

Procedure

Examine the metal shaft of the part of the earphone or headset that is inserted into a portable radio. You will notice that just below the tip of the shaft there is a plastic spacer. Clip on one of the wires below this spacer. Then clip on the other wire above this spacer.

To test that the wires are properly connected to the earphone or headset, take the unconnected ends of the two wires and touch them to an AA-size battery. One wire should touch the positive end of the battery, while the other is touching the negative end of the battery. Place the earphone or headset to your ear. If your connections are made correctly, you should hear a crackling sound in the earphone or headset. If you do not hear a crackling sound, check your connections carefully.

Place a small piece of aluminum foil, about five inches (13 centimeters) square, on a small plate. Using a spoon, make a puddle of tomato juice on the aluminum foil. The puddle of tomato juice should be slightly larger than a penny. Next, place a new, shiny penny face down in the puddle of tomato juice.

Using the alligator clip, attach one of the wires connected to the earphone to one of the edges of the aluminum foil. Take the end of the other wire and touch the alligator clip to the penny. Move the alligator clip over the penny.

Observations

Do you hear a crackling sound when you touch the alligator clips to the penny in the puddle of tomato juice? What do you hear when you move the alligator clip over the penny? What do you hear when you stop touching the penny with the alligator clip?

Discussion

In this experiment you made a simple battery with a penny, aluminum foil, and tomato juice. You completed a circuit with your battery by touching one of the wires attached to the earphone or headset to the penny, while touching the other wire to the aluminum foil. When you completed the circuit, a flow of electrons was produced by your battery. The crackling sound you heard was caused by the earphone or headset converting electrical energy from your battery into sound energy.

In your battery, the aluminum in the aluminum foil loses electrons. The other part of the reaction is more complex. Either the acid in the tomato juice or copper ions (that form when the copper metal in the penny reacts with the acid in the tomato juice) gain the electrons lost by the aluminum.

The main types of batteries are known as primary and secondary batteries. Dry cell batteries, like the ones used in flashlights and portable radios, are primary batteries. Another important primary battery is the mercury battery. Mercury batteries are typically small and flat. They are used to power cameras, watches, hearing aids, and calculators.

An advantage of primary batteries is that they are generally inexpensive. One disadvantage is that they cannot be recharged. When the chemical substances in the primary batteries are used up, the battery is dead.

Lead storage batteries and nickel-cadmium (NiCad) batteries are examples of secondary batteries. Car batteries are lead storage batteries. Flashlight batteries that are rechargeable are NiCad batteries. Secondary batteries are more expensive than primary batteries. However, unlike primary batteries, lead storage batteries and NiCad batteries can be recharged repeatedly.

Other Things to Try

Repeat this experiment using other coins such as a dime, nickel, or quarter. Do any of these coins cause a louder crackling sound in the earphone or headset?

Repeat this experiment using a nail instead of a coin. Can you make a battery with other juices? To find out, repeat this experiment with other juices such as lemon and orange juice. What do you observe?

Exercises

Fill in the blank: A battery produces ___________________ energy from _________________________ energy.
Another name for a battery is:
1. Solar array
2. Voltaic cell
3. Nuclear reactor
4. Fusion cell
As one chemical loses electrons, what happens to the other chemical?
1. It loses electrons
2. It gains electrons
3. Nothing
4. It decomposes
When will a battery run out?
1. When its batteries run out
2. When its chemicals are used up
3. When all the electrons are gone
4. When the bunny stops drumming

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Can Insulation Save Energy?

Friday November 4, 2011

An insulator is a substance that partly blocks or slows the flow of heat through it. Styrofoam is a lightweight plastic used in drinking cups. Styrofoam is a good insulator. A cooler or ice chest that is made of Styrofoam or some other insulator tends to block the flow of heat through it.

Heat flows into buildings during warm summer months and from buildings during cold winter months. Energy must be used to cool buildings in the summer and heat them in the winter. Since insulation can slow the flow of heat, the use of insulation in buildings can save energy.

Some common home and building insulation materials include Styrofoam, polyurethane foam, and fiberglass. These materials are all good insulators, which means that they are poor conductors of heat. Placing these insulating materials on attic floors or in building walls tends to trap heat inside during the cold winter and keep heat out during the hot summer.

Plastic foams filled with trapped gas tend to block heat flow. The chemicals used to make polyurethane foam can be sprayed directly into the spaces between walls. These chemicals produce carbon dioxide gas and polyurethane plastic. The gas tends to spread the polymer apart so the weight is mostly plastic but the volume is mostly trapped gas. Polyurethane also is used to insulate refrigerators, refrigerated trucks, pipes, and building walls.

Fiberglass insulation is frequently used in attic floors to insulate homes. Also, fiberglass insulation is used to insulate the Trans-Alaska pipeline. This pipe carries oil 800 miles from Prudhoe Bay in northern Alaska to Valdez in southern Alaska. The crude oil that travels through this pipe is easier to pump if it is hot. An insulated pipeline requires less energy to keep the oil hot.

Energy conservation becomes more and more important as energy costs rise. A great deal of energy is used to cool buildings in summer and heat buildings in winter. Less energy will be needed if buildings are well insulated and energy is not wasted.
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Materials

Two large, plastic cups
Small, insulated ice chest or cooler (Styrofoam or plastic)
Ice
Watch or clock

Procedure

Completely fill each plastic cup with ice. Set one plastic cup out in the room. Set the other plastic cup of ice inside the small ice chest or cooler. Close the lid of the ice chest and leave both cups undisturbed.

Observe the cup of ice left out in the room once every hour. When all the ice has changed to water in the cup left out in the room, open the smaller cooler and observe the cup of ice inside. Continue to check on the cup of ice in the cooler about once an hour and see how long it takes to melt.

Observations

How long does it take for the cup of ice in the room to melt and change to water? When all the ice has melted in the cup in the room, is there still ice in the cup in the ice chest? How long does it take for the ice in the cooler to melt?

Discussion

You should find that the ice in the room melts faster than the ice inside the ice chest. When the ice in the room has all melted and only water remains, the cup inside the insulated cooler may still be mostly ice. Even though both cups were filled with the same amount of ice, they did not melt at the same time.

The temperature in the room is much warmer than the temperature of the cold ice. Since heat always flows from a higher temperature to a lower temperature, the heat in the room flows or moves into the ice and causes it to melt.

Other Things to Try

Repeat this experiment with a larger amount of ice, and you may see a greater difference between insulated and uninsulated containers. Try filling a bucket and an ice chest with equal amounts of ice, and set both containers outside on a warm day. How long does it take the ice in the bucket to melt? How long does it take the ice in the ice chest to melt?

You can reverse the experiment by comparing the flow of heat from the inside of a cup to colder surroundings. Use hot water from a sink faucet to partially fill a Styrofoam cup and a glass cup. Place the Styrofoam cup inside two other Styrofoam cups and cover the top with several layers of aluminum foil. Next place the Styrofoam cups and the glass cup inside the refrigerator and compare how long it takes for the water to cool.

Fill a thermos bottle with hot water. Wait about four hours and check the temperature of the water. Continue to check the temperature about every two hours to find out how long the thermos bottle can keep the water warm. A thermos bottle has glass walls with a vacuum between them and silvered surfaces to reflect heat. The vacuum in a thermos makes an excellent insulator because there are few gas molecules to transfer heat.
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Can a Salt Be Used for Heating and Cooling?

Friday November 4, 2011

Cooling and heating are opposite processes. Cooling is the removal of heat energy from an object or space and heating is the addition of heat energy to an object or space. We use these opposite processes a great deal in our daily lives. For example, in the kitchen we use the cooling provided by a refrigerator to keep food cold. We also use the heat from a stove to cook food.

Nearly 75 percent of the energy used by the average family household in the United States goes for cooling and heating purposes. Air conditioning and refrigeration are the major cooling requirements of a home, while water and space heating are the most important heating requirements.

In the experiments that follow you will learn more about cooling and heating. You will also learn alternative ways of cooling and heating, using such unusual materials as gases, salts, water, and trees.
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Materials

Epsom salt
Aluminum pie pan
Water
Oven
Insulated mitt
Two small, zipper-close, plastic bags
Sink
Measuring cups

Procedure

ASK AN ADULT TO HELP YOU WITH THIS EXPERIMENT. DO NOT USE THE STOVE BY YOURSELF.

Ask an adult to turn on the oven and to set the temperature of the oven to 450° F

(232°C). Pour one-half cup of Epsom salt into an aluminum pie pan and gently shake it to evenly spread the Epsom salt over the bottom of the pan. Place the pie pan in the oven. Heat the Epsom salt in the hot oven for thirty minutes.

Ask an adult to remove the pan of Epsom salt from the hot oven using an insulated mitt. Place the pan on the stovetop and allow it to cool for ten minutes. Make sure the oven is turned off.

Add one-quarter cup of the Epsom salt that was not heated in the oven to a small plastic zipper-close bag. Next add one-quarter cup of room temperature water to the bag, seal, and shake the bag. Feel the temperature of the outside of the bag.

Next add one-quarter cup of the cooled Epsom salt that was heated in the oven to the second zipper-close bag. Add one-quarter cup of room temperature water to the bag and seal the bag. Give the bag a couple of shakes and then feel the outside of the bag.

When you are finished with this experiment, pour the contents of both bags down a sink drain. Then flush the bags and the sink with water. Also rinse out the aluminum pie pan with water. DO NOT DRINK ANY OF THE LIQUID AND DO NOT EAT ANY OF THE EPSOM SALT. EPSOM SALT CAN MAKE YOU SICK IF YOU EAT IT.

Observations

Do you notice any difference in the appearance of the Epsom salt after it is heated in the oven? Does the bag containing the water and the Epsom salt that was not heated feel warm or cool after shaking? Does the bag containing the water and the Epsom salt that was heated feel warm or cool after shaking?

Discussion

Epsom salt is a hydrate of the salt called magnesium sulfate. A hydrate is a chemical substance containing water combined with another chemical substance (usually a salt). The water molecules in a hydrate are called waters of hydration. They can usually be removed from the hydrate by heating. The process of removing water from a hydrate is called dehydration.

In this experiment, when you heated the Epsom salt in the oven, you removed most of the water molecules (waters of hydration) in the salt.

A salt is made of positive and negative ions. Ions are charged atoms or groups of atoms. In Epsom salt, magnesium ions are positive and sulfate ions are negative. The waters of hydration surround these ions in Epsom salt.

You should find that the bag containing water and the dehydrated Epsom salt feels warm. The bag containing water and the hydrated Epsom salt feels cool. When dehydrated Epsom salt is mixed with water, heat is given off. When hydrated Epsom salt is mixed with water, heat is absorbed. When something gives off heat it feels warm, while something that absorbs heat feels cool.

Energy is required to remove individual ions from a salt crystal. However, energy is given off when the individual ions that break away from the crystal become surrounded by water molecules that are dissolving the salt. If more energy is required to remove individual ions from a salt crystal than is given off when the ions become surrounded by water, then the salt solution becomes cold. If more energy is given off when the ions become surrounded by water than is needed to remove individual ions from a salt crystal, then the salt solution becomes warm.

When hydrated Epsom salt dissolves in water, more energy is required to remove the magnesium and sulfate ions (and the waters of hydration) from the crystals than is given off when the magnesium and sulfate ions become surrounded by the dissolving water molecules.

This is why the bag containing the unheated Epsom salt became cold when you added water.

On the other hand, when dehydrated Epsom salt dissolves in water, more energy is given off by the ions becoming surrounded by water molecules than is needed to break the magnesium and sulfate ions from the crystals. This is why the bag containing the dehydrated Epsom salt became warm when you added water.

Most instant hot packs and cold packs that are available in drugstores work on the principle just discussed. When the cold or hot pack is needed, the bag is squeezed to cause the water and salt to mix. Depending on the salt used in the pack, energy is either absorbed (cold pack) or given off (hot pack). Ammonium nitrate is the most commonly used salt in cold packs. And calcium chloride is the most commonly used salt in hot packs.

Other Things to Try

Repeat this experiment using a thermometer to measure the temperature change when the Epsom salt is dissolved in water. Use the thermometer to measure the temperature change when dehydrated magnesium sulfate is dissolved in water.

Repeat this experiment using table salt. Do you observe a temperature change when the table salt dissolves in water?
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How Can Shade Trees Keep Things Cool?

Friday November 4, 2011

Having shade trees around a house can decrease the cost of cooling the house with air conditioning. A house not shaded from the sun absorbs some of the light from the sun and heats up the outside surface of the house. If the house is poorly insulated, some of this heat will penetrate into the house, heating up the inside. The air conditioner will use more energy to remove this added heat.

Properly designed roof overhangs can significantly decrease the heating and cooling costs of a house. Because the earth’s axis is tilted, the sun is lower in the winter in the northern hemisphere. In the summer, the sun is higher in the sky. A properly designed roof overhang allows sunlight in the winter to shine through windows and warm the furnishings in the rooms that receive the direct sunlight. This reduces the heating cost in the winter. In the summer, the overhang blocks the sunlight from shining into the window and heating the furnishings. This reduces the cooling cost in the summer.
[am4show have=’p8;p9;p22;p49;p84;’ guest_error=’Guest error message’ user_error=’User error message’ ]
Materials

Two large, glass jars
Shady tree
Water
Thermometer (optional)

Procedure

You will want to do this experiment on a warm, sunny day. Fill both large, glass jars nearly full with water. Place one of the jars outdoors in a spot where sunlight will strike it for several hours. Place the other jar outdoors under a shady tree.

After three hours, feel the water in the jar that was left in the sun. Next feel the water in the jar kept under the shady tree. If you have a thermometer, check the temperature of the water in each jar. Also check the air temperature with the thermometer.

Observations

Does the water in the jar left in the sun feel warmer or cooler than the water in the jar left under the shady tree? If you are using a thermometer, what is the temperature of the air and of the water in each jar? What is the temperature difference of the water in the two jars?

Discussion

The water in the jar that was left in the sun should feel much warmer than the water in the jar left under the shady tree. The temperature difference of the water in the two jars will vary depending on the air temperature and wind conditions. On a hot, sunny day you may find that the temperature of the water in the jar left in the sun is over 18° F (10° C) warmer than the air temperature and the temperature of the water in the jar kept in the shade.

The jar of water left in the sun is constantly bathed with light energy from the sun. Some of this light energy is absorbed by the glass jar and the water in the jar. The light energy that is absorbed by the glass jar and the water is converted into heat energy. This is why the jar of water becomes warm after being in the sun for several hours.

The tree shades the other jar of water from the sun. The jar of water under the tree does not absorb light energy directly from the sun as the other jar did. Instead, much of the light energy from the sun is absorbed and used by the tree.

Since the jar of water under the tree does not absorb light energy directly from the sun, it remains cooler than the jar of water kept in the sun. You may even find that the temperature of the water in the jar shaded from the sun is a few degrees cooler than the air temperature. This is caused by water evaporating from the jar. Heat energy is removed when a liquid evaporates, and the liquid becomes slightly cooler.

Other Things to Try

Repeat this experiment at different times of the day. Do you get similar results? Repeat this experiment when it is cloudy. How does the difference in the temperatures of the jars of water compare on sunny and cloudy days.
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Can the Evaporation of Water Be Used for Cooling?

Friday November 4, 2011

The evaporation of water for cooling purposes is called evaporative cooling. An important example of this type of cooling is the removal of body heat by humans through sweating. When your body needs to cool, perspiration is released to the surface of your skin where it evaporates. The evaporation of the water in the perspiration causes your skin to cool.

Breezes feel particularly cooling when you have perspiration on your skin. This is because the increased movement of air over your body evaporates more water from your skin than still air does. Water on your skin evaporates more slowly when the humidity is high. This is because the humid air already contains much water vapor. Humid air absorbs less water as vapor than dry air.

Electrical power plants that burn fossil fuels or use nuclear energy to generate electricity use huge water cooling towers for cooling purposes. The water to be cooled is pumped to the top of the tower and allowed to drip down through the tower. As the water moves down the tower, air from the bottom of the tower moves up through the tower, evaporating some of the falling water. The heat lost by the evaporating water cools the remaining water that is collected in a basin under the tower. One pound of water that evaporates in a tower can lower the temperature of 100 pounds (45 kilograms) of other water by nearly 50°C (100°F).
[am4show have=’p8;p9;p22;p49;p84;’ guest_error=’Guest error message’ user_error=’User error message’ ]
Materials

Unglazed clay flower pot
Plastic bowl
Unglazed clay saucer
Water
Modeling clay
Thermometer (optional)

Procedure

Make sure to use an unglazed clay flowerpot for this experiment. Most unglazed clay flowerpots have an orange-red color and rough surfaces. The bottom of the unglazed clay saucer should have a diameter larger than the top diameter of the flowerpot. (Flowerpots and saucers can be purchased at most hardware and plant stores.)

Most clay flowerpots have drainage holes. Check to see if your clay flowerpot has a drainage hole in the bottom. If the one you are using has a hole, seal it with a piece of modeling clay. Add some water to the pot to make sure your seal is watertight.

Place the clay flowerpot and plastic bowl outside on a hot, sunny day and in a spot where they will get plenty of sunshine. Fill both the clay flowerpot and the plastic bowl nearly full with water. Place the clay saucer on top of the flowerpot and fill it with water.

Every hour for three hours, place your hands around the outside of the plastic bowl of water. Then place your hands around the outside of the clay pot filled with water. Next dip your hand into the plastic bowl of water. Remove the clay saucer from the flowerpot and dip your same hand into the pot of water. If you have a thermometer, place it in the plastic bowl of water. Read the temperature on the thermometer after it has been in the water thirty seconds. Next place the thermometer in the clay pot of water. After thirty seconds read the temperature of the water in the clay pot.

Observations

Does the outside of the clay flowerpot appear wet and feel wet after it has been outside several hours?

Does the outside of the plastic bowl feel warmer or cooler than the outside of the clay flowerpot after both containers have been in the sun several hours? Does the water in the clay flowerpot feel warmer or cooler than the water in the plastic bowl?

If you are using a thermometer, what is the temperature of the water in the plastic bowl? What is the temperature of the water in the clay pot?

Discussion

You should find that soon after you add the water to the unglazed clay flowerpot, the outside of the clay pot looks and feels wet. The outside of the clay flowerpot should feel cooler than the outside of the plastic bowl. Also, the water inside the flowerpot should feel much cooler than the water inside the plastic bowl. In fact, if you measured the temperatures of the water in both containers you may have found that the water in the clay pot was cooler by as much as 18°F (10°C). The temperature difference will depend on the air temperature, the humidity, and wind. The higher the humidity and the less wind there is, the smaller the temperature difference between the two containers will be.

The outside of the clay flowerpot becomes wet because water inside the flowerpot moves through the wall of the clay pot. When water reaches the outside surface of the clay pot, it can evaporate. When the water evaporates, it changes from a liquid to a gas or vapor.

Heat energy is required for water to evaporate. This heat energy comes from the clay pot and the water inside the clay pot. When the water evaporates and removes heat from both the pot and water, the temperature of both the pot and water decreases.

Water evaporates from the plastic bowl as well. However, since water cannot move through the plastic, water evaporates only from its surface in the plastic bowl. More heat is removed from the clay pot than the plastic bowl because water is evaporating from a larger area. This is why the outside of the clay pot and the water inside it should feel cooler than the outside of the plastic bowl and the water inside it.

Other Things to Try

Repeat this experiment and record the temperatures of the water in the two containers with a thermometer every hour for five or six hours. Is the temperature of the water in the clay pot always lower than the temperature of the water in the plastic bowl?

If you are ever near the bottom of a waterfall, notice that the air temperature around the waterfall is cooler than air away from the waterfall. Can you explain why?
[/am4show]

Can Expanding Gases Be Used for Cooling?

Friday November 4, 2011

In a typical air conditioning or refrigeration system, a liquid at high pressure is allowed to pass through a valve from a higher pressure to a lower pressure. As the liquid enters the lower pressure region, it changes from a liquid to a gas. This change causes a cooling effect. The liquid cools as it changes to a gas.

In a cooling system, such as a refrigerator or air conditioner, this cold gas is used to cool a box (refrigerator) or a room (air conditioner). Then the cool gas is forced through a compressor pump where it undergoes a warming effect and changes back to a liquid. This excess heat is removed before the liquid is expanded to a gas again. In an air conditioner, the excess heat is blown outside.

Special molecules containing chlorine, fluorine, and carbon atoms are used in most cooling systems. These Freon or chlorofluorocarbon (CFC) molecules are used because they are stable, nontoxic, and will not burn.

In recent years, scientists have discovered that these Freon or CFC molecules are damaging the earth’s ozone layer. Ozone molecules in the upper atmosphere block harmful ultraviolet radiation from reaching the earth. Because these CFC molecules are so stable they tend to stay in the atmosphere for many years, during which time they gradually spread to the upper atmosphere.

In the upper atmosphere, CFC molecules can release chlorine atoms. These atoms cause a chemical reaction that breaks apart ozone. One chlorofluorocarbon molecule may destroy thousands of ozone molecules. Scientists and engineers are looking for new methods of cooling and new gases that are less damaging to the ozone layer.

The main energy used in operating a cooling system is the energy required to run a compressor to force a gas to a higher pressure, where it will change back to a liquid. This energy is normally supplied by electricity or by burning natural gas to run a compressor pump. However, there are systems in which solar energy is used to supply the energy needed for cooling.
[am4show have=’p8;p9;p22;p49;p84;’ guest_error=’Guest error message’ user_error=’User error message’ ]
Materials

Thermometer (outdoor type)
Newspaper
Can of Lysol® spray (use pressurized aerosol can, not pump spray)

Procedure

HAVE AN ADULT HELP YOU WITH THIS EXPERIMENT. LYSOL®, LIKE OTHER SPRAY CANS, SHOULD NOT GET NEAR A FLAME, AND THE CONTENTS SHOULD NOT GET IN YOUR EYES.

Set a can of Lysol® spray in the room where the experiment will be done and wait one hour. Observe the temperature of the room by reading the temperature on a thermometer. The can of Lysol® spray should be the same temperature as the room.

Place about ten sheets of newspaper, one on top of the other, on the floor. Have an adult hold the thermometer in one hand and the spray can in the other hand. These items should be held above the newspaper to catch Lysol® liquid that may drip off the thermometer. The adult should hold the nozzle of the Lysol spray can about four inches from the bottom of the thermometer. Have the adult spray the bottom of the thermometer for twenty seconds.

While the adult sprays the Lysol® on the thermometer, you should observe the temperature. After he or she stops spraying, continue to observe the temperature on the thermometer for several minutes.

Observations

What is the temperature of the room and the can of Lysol® spray? Does the temperature drop while the Lysol® is sprayed? What is the temperature while gas is sprayed from the can on the thermometer? What happens to the temperature after the spraying is stopped?

Discussion

You should find that the temperature on the thermometer drops as the Lysol® is sprayed on it. The temperature may decrease by 14° F (8° C) or more. After the spraying is stopped, the temperature may drift slightly lower, and then should gradually increase to the original temperature of the room.

If you shake the can of Lysol®, you should hear the sound of a liquid sloshing or moving inside the can. The can contains gas and liquid. When the can is sprayed, the pressurized gas escapes and liquid expands to a fine mist or vapor (gas). This change, from a higher pressure to a lower pressure gas and from a liquid to a gas, causes a cooling effect. You observe this cooling when you see the thermometer’s temperature decrease.

Other Things to Try

Open a two liter soft drink bottle that has been out in the room for several hours. As you open the bottle, let the carbon dioxide gas that escapes and causes a hissing sound fall on your lips. Does the gas coming out of the soft drink bottle feel hot or cold?
[/am4show]

Can the Sun Be Used to Heat Water?

Friday November 4, 2011

The energy of sunlight powers our biosphere (air, water, land, and life on the earth’s surface). About 50 percent of the solar energy striking the earth is converted to heat that warms our planet and drives the winds. About 30 percent of the solar energy is reflected directly back into space. The water cycle (evaporation of water followed by rain or snow) is powered by about 20 percent of the solar energy.

Some of the sunlight that reaches the earth is used by plants in photosynthesis. Plants containing chlorophyll use photosynthesis to change sunlight to energy. Since these green plants form the base of the food chain, all plants and animals depend on solar energy for their survival.

When the sun is overhead, about 1,000 watts of solar power strike 1 square meter (10.8 square feet) of the earth’s surface. Using solar cells, this solar energy can be converted to electricity. However, because sunlight cannot be converted completely to electricity, it takes at least a square meter of area to gather enough sunlight to run a 100-watt light bulb.

Solar energy is still more expensive than other methods of generating electricity. However, the cost of solar electricity has greatly decreased since the first solar cells were developed in 1954.

It has been proposed that panels of solar cells on satellites in orbit above the earth could convert solar energy to electricity twenty-four hours a day. These huge solar power satellites could convert electrical energy to microwaves and then beam these microwaves to Earth. At the earth’s surface, tremendous fields covered with antennas could convert the microwave energy back to electricity.

It would take thousands of astronauts many years to build such a complicated system. However, there are many practical uses of solar energy in use today. These uses include heating water, heating and cooling buildings, producing electricity from solar cells, and using rain and snow from the water cycle to power electrical generators at dams.

In the following experiments, you will examine the use of solar energy in heating water, .cooking foods, concentrating sunlight, and producing electricity.
[am4show have=’p8;p9;p70;p22;p49;p75;p84;’ guest_error=’Guest error message’ user_error=’User error message’ ]
Materials

Paint brush
Thermometer (outdoor type)
Newspaper
Aluminum foil
Water
Large, plastic glass
Empty aluminum 12-ounce (355 milliliter) soft drink can
Black paint or spray paint (flat, not shiny)

Download Student Worksheet & Exercises

Procedure
Go outside and spread a sheet of newspaper on the ground. Place an empty aluminum soft drink can on the newspaper. Have an adult help you paint the outside of the aluminum can. You can use a brush and can of paint or spray paint. Be sure to use paint that is suitable for a metal surface. The paint should give you a flat (not shiny) surface. Be sure not to get the paint on anything but the can and newspaper. After painting, set the can where the paint can dry overnight.

You will need to do the rest of this experiment on a warm, sunny day. Partially fill a large, plastic glass with cool tap water. Check the temperature of the water with a thermometer. Pour the water from the plastic glass into the painted black can, completely filling the can. Pour out any extra water remaining in the plastic glass. Cover the can’s opening with a small piece of aluminum foil about the size of a quarter.

Set the black can outside in a sunny spot. Pick a place where the sun will shine on the can all day. (You do not want the can to be in the shade.)

After the can of water has been in the sunshine for about four hours, pour the water into the large, plastic glass. Check the temperature of the water with the thermometer. Feel the outside of the can.

Observations

What was the temperature of the cool tap water when it was first placed into the black can? What is the temperature of the water after it was heated in the can for four hours? Does the outside of the can feel hot?

Discussion

You should find a significant increase in the temperature of the water that was left in the black can during the day. The tap water initially may be about 21°C (70°F), but after the water has been heated inside the can, the temperature should rise to more than 38°C (100°F). The exact temperature you achieve in your miniature, solar water heater (black can) will depend on your location and the time of year. However, you should find that the water temperature will go much higher than the temperature of the outside air.

The electromagnetic radiation from the sun includes ultraviolet, visible, and infrared radiation. Ultraviolet radiation is the type of sunlight that causes tanning of skin. Visible radiation is the type of sunlight we see with our eyes. Infrared radiation is the type of sunlight that we feel as heat when the sun is shining on our skin. All these forms of solar radiation have energy associated with them.

When solar energy from the sun’s electromagnetic radiation strikes a black surface, solar energy is converted to heat energy and the surface is warmed. Other colors will absorb solar energy, but lightly colored surfaces tend to reflect the light, while darker colors absorb the solar energy. You may have noticed this difference if you ever walked barefoot on a dark road on a hot summer day.

Direct solar energy is not hot enough for cooking. The higher temperatures required for cooking or for changing water to steam require concentrating the energy of sunlight with mirrors or lenses. However, directly absorbed solar energy is hot enough for heating homes and producing hot water with little or no energy costs.

When we turn on a hot water faucet at a sink, water is taken from a hot water tank. In industrialized countries, we usually heat water using electricity or natural gas and store the hot water in this insulated tank. However, around the world, there are millions of solar heaters used for heating water.

Solar water heaters use a black metal plate covered with insulated glass. These solar heaters are usually placed on rooftops to receive the maximum amount of sunlight. Water flows through tubes beneath the black metal plates. Solar energy heats the black metal plates and the water passing in tubes underneath the plates. The heated water is piped to a storage tank, where it is kept until needed. If the location of the solar heater is not consistently sunny, then an auxiliary heater-using electricity or natural gas-is sometimes used to heat the water.

Other Things to Try

Repeat this experiment covering the black can with a large glass jar. This glass should help trap the heat and make the water get even hotter. What is the maximum temperature you can get with this type of solar heater?

Repeat this experiment and check the temperature of the water each half hour for three hours during the middle of the day. Quickly check the temperature of the water, then return the water to the black metal can. Write down the time that you checked the water, and next to the time, write down the temperature. How long does it take for the water to reach the maximum water temperature?

Repeat this experiment with an unpainted can and a painted can. After one hour, how do the temperatures of the water in each can compare?

Repeat this experiment on a cloudy day. Does the water in the can get as hot without sunshine?

Exercises

The solar energy that hits the earth is responsible for what proportion of the energy on our planet?
1. Nearly all of it
2. About 50%
3. 25%
4. None of these
Name one way that the physical earth uses the earth’s energy:
True or false: Solar power is generally less expensive than other forms of power.
1. True
2. False

[/am4show]

How Can the Sun Be Used for Cooking?

Friday October 28, 2011

Cooking involves heating food to bring about chemical changes. Sometimes foods are heated simply because the food tastes better warm than cold. In making tea, we sometimes heat water to help dissolve tea or help dissolve sugar if the tea is sweetened.

Normally the water used to make tea is heated on a range top or in a microwave oven. Using a range or microwave oven requires buying energy in the form of electricity or natural gas. Using a solar cooker does not require any energy costs because it uses a freely available renewable energy source-the sun.

A curved mirror in a bowl-like shape can focus reflected sunlight at a spot for cooking. A mirror about 1.5 meters (5 feet) across can generate a temperature of 177°C (350°F) and boil a liter of water in about fifteen minutes. In sunny areas of the world, solar cookers can be used instead of burning firewood for cooking.

Another way reflected and focused sunlight is used is to generate electricity. In southern California in 1982, a solar-thermal plant was built that can generate ten million watts of electrical power. This plant consists of 1,818 mirrored heliostats. A heliostat is a device that moves to track the sun across the sky and to reflect the sunlight at the same point. Each heliostat has twelve mirrors, and all the heliostats reflect sunlight to the same spot. The reflected light is directed at the top of a 90-meter (295-foot) tall tower. The concentrated sunlight is used to boil water and heat the steam up to 560° C (1,040 ° F). The steam turns a turbine that powers a generator to produce electricity.

One obvious disadvantage of solar-thermal plants is that they only operate when the sun is shining. The heat energy can be stored for a time by heating up a liquid or melting salt. Or the energy can be used to break water into hydrogen and oxygen. The hydrogen can then be stored and burned later to produce water and release energy.
[am4show have=’p8;p9;p22;p49;p75;p84;’ guest_error=’Guest error message’ user_error=’User error message’ ]
Materials

Three clear, clean plastic cups
Two small tea bags
Aluminum foil
Watch or clock
Measuring cup
Water
Two spoons
White sheet of paper
Plastic pan (4 inches deep and 12 inches across is a convenient size but other sizes can be used)

Download Student Worksheet & Exercises

Procedure

You will need to do this experiment on a warm, sunny day.

Use two sheets of aluminum foil and place them crosswise to completely cover the bottom and sides of a plastic pan. Try to arrange the aluminum foil so that it is smooth and curved like a bowl. The aluminum foil will help to reflect the solar energy and concentrate the light and heat toward the center of the pan. Place this aluminum covered pan outside in a warm, sunny spot where the sunlight will shine directly on it.

Add one cup of water to each of two plastic cups. The water you add to the cups should be neither hot nor cold, but about temperature. Place one cup of water in the middle of the pan. Turn the empty plastic cup upside down and place it on top of this cup. Leave this “solar cooker” undisturbed for one hour. The other cup of water should remain inside.

After one hour, gently place one tea bag in each of the water-filled cups. Wait ten minutes and then lift the tea bag out of each cup. Using a spoon, stir each cup of tea. Place both cups of tea on a white piece of paper and look down on the two cups to compare their darkness. Put your finger in each cup of tea to compare their temperatures.

Observations

Which cup of tea is a darker color? Which cup of tea is warmer?

Discussion

You should find that the water left in the “solar cooker” is darker and warmer than the water left in the shade. The darker color indicates that more tea has gone into or dissolved in the warmer water.

Other Things to Try

Place your “solar cooker” in the sun as in this experiment, but place one plastic cup upside down in the middle of the pan. Put a pat of margarine or butter on top of this cup. Will the sun melt this butter? How long does it take to melt? Repeat this activity with a piece of soft cheese and determine if the solar heater will melt the cheese. In a more carefully made solar cooker, the reflective surfaces are angled to focus a large amount of sunlight in one spot and the temperatures obtained are much higher than in your cooker.

Set one cup of water in your “solar cooker.” Set a second cup of water in the sunshine and leave both cups for one hour. Use a thermometer to check the temperature of each cup of water. Does your “solar cooker” help focus the sun’s rays and increase the temperature?

Exercises Answer the questions below:

What type of solar energy are we seeing in this experiment?
1. Solar fusion
2. Solar voltaic
3. Solar thermal
4. Radiation potential
Name two ways that the earth’s systems depend on the sun:
What is one advantage of solar thermal energy? What is one disadvantage?
1. Advantage:
2. Disadvantage:

Can Solar Energy Be Concentrated?

Friday October 28, 2011

The curved shape of the magnifying lens causes light rays to bend and focus on an image. When we look through the lens, we can use it to make writing or some other object appear larger. However, the magnifying lens can also be used to make something smaller. The light from the bulb is bent and focused on the wall when the lens is held far from the lamp and close to the wall. The image is much brighter than the surroundings. This is because all the light falling on the surface of the lens is concentrated into a much smaller area.

When sunlight is concentrated by passing it through a lens, the result can be an intensely bright and not spot of light. Even a small magnifying glass can increase the intensity of the sun enough to set wood and paper on fire. We are using a light bulb rather than sunlight for this experiment because concentrated sunlight Can be very harmful to your eyes. NEVER LOOK AT A CONCENTRATED IMAGE OF THE SUN.

The United States Department of Energy’s National Renewable Energy Laboratory in Colorado uses solar energy to operate a special furnace. This high-temperature solar furnace uses a lens to concentrate sunlight. A heliostat (a device used to track the motion of the sun across the sky) is used so that the image reflected from a mirror is always directed at the same spot. The lens is used to concentrate sunlight from a mirror to an area about the size of a penny. This concentrated sunlight has the energy of 20,000 suns shining in one spot.

In less than half a second, the temperature can be raised to 1,720° C (3,128° F) which is hot enough to melt sand. This high-temperature solar furnace is being used to harden steel and to make ceramic materials that must be heated to extremely high temperatures.

Concentrated sunlight also has been used to purify polluted ground water. The ultraviolet radiation in sunlight can break down organic pollutants into carbon dioxide, water, and harmless chlorine ions. This procedure has been successfully carried out at the Lawrence Livermore Laboratory in California. In the laboratory, up to 100,000 gallons of contaminated water could be treated in one day.
[am4show have=’p8;p9;p22;p49;p84;p85;’ guest_error=’Guest error message’ user_error=’User error message’ ]
Materials

Lamp with a single incandescent bulb
Magnifying lens

Download Student Worksheet & Exercises

Procedure

The results of this experiment may be easiest to observe if done at night in a dark room.

Ask an adult to remove the lamp shade from a lamp that uses a single incandescent bulb. An incandescent bulb is the type that gets quite hot when used. Turn on the lamp. Turn off all the other lights in the room.

Stand about two feet from the wall that is the greatest distance from the lamp. There should be nothing between you and the lamp bulb. Place the magnifying glass on the wall so that the lens is flat against the wall. Now, slowly move the lens away from the wall and toward the light. Keep the lens parallel to the surface of the wall. As you move the lens outward, watch the wall.

Observations

Does an image of the lamp appear on the wall? How bright is this image? How big is this image?

Discussion

You should see an upside down image of the light bulb appear as you move the magnifying lens away from the wall. The image should be much brighter than the area around it and much smaller than the size of the real bulb. The image may be only about the size of your fingernail or smaller.

Other Things to Try

Trace the exact size and shape of the magnifying lens on a piece of paper. Cut out this piece of paper and tape in on the wall. Focus the image of the lamp on this piece of paper and copy the bulb image on the paper. Compare the size of the bulb image to the size of the piece of paper. How much bigger is the lens than the focused image of the bulb? Use this ratio of sizes to estimate the increase in the brightness of the image.

Can you explain why the image of the bulb is upside down when it is projected on the wall? See if you can find information about optics in a book or encyclopedia that could help you explain this reversal of the image.

Repeat this experiment using two magnifying lenses. Observe the effect of moving the positions of the two lenses relative to each other and the wall.

Exercises Answer the questions below:

Name three uses for solar energy:
What type of heat energy is transmitted by the sun?
1. Conduction
2. Convection
3. Plasma
4. Radiation
Circle the following phenomena influenced by the sun:
1. Pressure
2. Climate
3. Weather
4. Wind

[/am4show]

Can Electricity Be Made From Sunlight?

Friday October 28, 2011

The solar cell you are using for this experiment is made from the element silicon. Silicon solar cells consist of two thin wafers of treated silicon that are sandwiched together. The treated silicon is made by first melting extremely pure silicon in a special furnace. Tiny amounts of other elements are added which produce either a small positive or negative electrical charge.

Usually boron is added to produce a positive charge and phosphorus is added to produce a negative charge. The addition of these other elements to pure silicon to produce an electrical charge is called doping.

After being doped, the molten silicon is allowed to cool. As it cools, the doped silicon grows into a large crystal from which very thin wafers are cut. A wafer cut from a large crystal of silicon doped with boron is called the positive or P-layer because it has a positive charge. A wafer cut from a large crystal of silicon doped with phosphorous is called the negative or N-layer.

To make a solar cell, a positive wafer (P-layer) and a negative wafer (N-layer) are sandwiched together. This causes the P-layer to develop a slight positive charge, and the N-layer to develop a slight negative charge. The solar cell is connected to a circuit by wires leading from the P-layer and the N-layer. When light falls on the surface of the cell, electrons are made to move from one layer to the other. Thus, a current of electricity flows through the circuit.

The first solar cells provided electrical power for space satellites and vehicles. Satellites and space vehicles are still big users of solar cells. Solar cells are now being used to provide electrical power for calculators and similar devices, weather stations in remote areas, oil-drilling platforms, and remote communication relay stations.

The best silicon cells convert only a small portion of the sunlight striking the cells into electricity. The efficiency of solar cells is about 15 percent. This means that 15 percent of the sunlight that strikes the cell is converted into electrical energy. The sunlight that is not converted into electricity either reflects off the surface of the cell or is converted into heat energy.
[am4show have=’p8;p9;p22;p49;p75;p84;’ guest_error=’Guest error message’ user_error=’User error message’ ]
Materials

Silicon solar cell
Two wires with alligator clips on each end of the wires
Earphone or headset for a portable radio
AA-size battery

Download Student Worksheet & Exercises

Procedure

For this experiment you will need a silicon solar cell. Small silicon solar cells are inexpensive and can be purchased at many electronic supply stores.

This experiment should be done on a bright, sunny day.

Examine the metal shaft on the part of the earphone or headset that is inserted into a portable radio. You will notice that just above the tip of the shaft there is a plastic spacer. Clip on one of the wires below this spacer. Then clip on the other wire above this spacer.

To test that the wires are properly connected to the earphone or headset, take the unconnected ends of the two wires and touch them to an AA-size battery. One wire should touch the positive end of the battery, while the other should touch the negative end of the battery. Place the earphone or headset to your ear. If your connections are made correctly, you should hear a crackling sound in the earphone or headset. If you do not hear a crackling sound, check your connections carefully.

Take the earphone or headset, with wires attached, and the solar cell outside into the sunshine. Ask a friend to join you. Your friend can help you hold the solar cell.

Place the earphone or headset to your ear. Ask your friend to hold one of the flat sides of the solar cell facing the sun. The two flat sides of the solar cell are different. In this experiment, you will determine which flat side must face the sun for the cell to generate electricity.

While your friend holds one of the flat sides of the solar cell facing· the sun, you hold one of the alligator clips on the side of the cell facing the sun. At the same time touch the other alligator clip to the opposite side of the cell. As you hold the alligator clips to the cell, avoid blocking the sunlight striking the solar cell.

Ask your friend to turn the solar cell over so that the side that was not facing the sun before now does. Touch a clip to the two sides of the solar cell.

After determining which side of the solar cell needs to face the sun to make a crackling sound in your earphone or headset, ask your friend to hold that side toward the sun. Touch the two alligator clips to each side of the solar cell. Move the alligator clip touching the bottom of the solar cell around the bottom side to keep making the crackling sound in your earphone or headset. Next block the sunlight striking the solar cell.

Observations

Describe the difference between the two sides of the solar cell. Which side must be facing the sun to cause crackling in the earphone or headset when you touch the clips to the solar cell? What happens to the crackling sound when you block the sunlight from striking the solar cell?

Discussion

When you examine your silicon solar cell, you will notice that the two flat sides of the cell are different. One side should have a silvery color, while the other side should appear dark. You should determine in this experiment that one side of the solar cell needs to face the sun for you to hear a strong crackling sound in the earphone or headset. The crackling sound is electricity, generated by the solar cell, passing through the earphone or headset.

Other Things to Try

Repeat this experiment on a cloudy day. Do you still hear a crackling sound in the earphone or headset? If you do hear a crackling sound, is it quieter than on a bright, sunny day?

Is there enough light in a room to cause the solar cell to make electricity? Try it yourself and see.

Exercises

If two electrodes become activated by a current, which way will the ions flow?
1. To the electrode of the same charge
2. To the electrode of the opposite charge
3. None of the above
What type of energy source is the solar panel most closely related to?
1. Biofuel
2. Chemical battery
3. Nuclear reactor
4. Plant energy
The solar cell’s efficiency is not very good. How much of its energy is converted into electricity?
1. 50 %
2. 80%
3. 30%
4. Less than all of these
Name one common use for solar cells:

[/am4show]

Can Water Be Heated With Composting Plant Material?

Friday October 28, 2011

Fossil fuels, which include petroleum, natural gas, and coal, supply nearly 90 percent of the energy needs of the United States and other industrialized nations. Because of their high demand, these nonrenewable energy resources are rapidly being consumed. Coal supplies are expected to last about a thousand years.

We must find other sources of energy to meet the increasing fuel demands of modern society. Important alternate sources of energy include: solar, wind, biomass, hydroelectric, geothermal, nuclear, and tidal energy.

One of the benefits of using alternate sources of energy is that many of them are “clean.” This means that they do not cause pollution. Also, many alternative energy sources are renewable energy sources. They are replaced naturally-such as plant life-or are readily available – such as the sun and wind. In addition, the use of renewable forms of energy will allow us to stretch out our current supply of fossil fuels so they will last longer.

In this chapter you will learn how biomass, or organic matter, can be an important energy source. Plants are the most important biomass energy source. Plant material can be burned directly-as with wood-or it can be converted into a fuel by other means. In the experiments that follow you will explore: how water can be heated by composting grass, how a peanut burns, and how corn syrup can be made into ethyl alcohol.
[am4show have=’p8;p9;p22;p49;p70;p84;’ guest_error=’Guest error message’ user_error=’User error message’ ]
Materials

Freshly cut grass clippings
Cooking thermometer (optional)
Empty two-liter plastic drink bottle
Rake
Water
Styrofoam cup

Procedure

Ask an adult to help you collect freshly cut grass clippings. You will need enough grass clippings to fill about two large grocery bags. Rake the grass clippings into a pile on a shady spot in the yard. In some parts of the country you will only be able to do this in the spring and summer months when grass grows.

Fill a two-liter plastic bottle with cold water. Starting at the top of the pile dig a hole down into the grass clippings just large enough for the plastic bottle. Place the plastic bottle in the hole, and then fill around it with grass clippings. The top of the plastic bottle should stick out of the pile of grass clippings slightly.

Check the water in the bottle after it has been in the pile of grass clipping for at least twenty-four hours. If you have a cooking thermometer, place it in the bottle for thirty seconds and then read the temperature on the thermometer. If you do not have a cooking thermometer, carefully remove the bottle of water from the pile of grass clippings. Feel the sides of the plastic bottle. CAUTION-THE BOTTLE MAY BE VERY WARM, SO AVOID BURNING YOURSELF. Pour some of the water into a Styrofoam cup and look for water vapor rising from the cup. Place the bottle back into the pile of grass clippings and check it again each day for several days.

Observations

After twenty-four hours in the grass clippings, is the water in the plastic bottle warm when you check it? If you check the water with a thermometer, what is the temperature of the water?

When you pour some of the water into a Styrofoam cup, do you see water vapor rising from the cup?

How many days does the water remain warm?

Does the pile of grass clippings become smaller after a few days? What does the pile of grass clippings look like when the water is no longer warm?

Discussion

The water in the plastic bottle should be warm after the bottle has been in the pile of grass clippings for twenty-four hours. The heat that warms the water comes from the pile of grass clippings, which is decomposing or composting.

The decomposition of dead plant and animal material is nature’s way of recycling important chemical substances. Complex chemical substances in dead plant and animal material are broken down into simple chemical substances during the process. These simpler chemical substances then become nutrients for living plants and soil animals.

Heat is given off during the decomposition process. The more material that is decomposing, the more heat is produced. In this experiment, a large amount of heat is given off by the decomposing grass clippings. This is because you started with a large pile of grass clippings, and grass clippings decompose quickly.

A pile of decomposing grass clippings can reach a temperature of over 71°C (160°F). The water in the bottle may absorb enough heat from the decomposing grass to reach a temperature as high as 60°C (140°F) after a day or two. For comparison, most household hot water heaters are set to deliver hot water with a temperature between 54°C (130°F) and 71°C (160°F).

Other Things to Try

How much water can you heat with composting grass clippings? To find out, repeat this experiment with a one-gallon plastic milk jug filled with water. Does the water in the jug become warm?

Repeat this experiment, but remove the bottle of water from the pile of grass clippings after twenty-four hours. Fill a second two-liter plastic bottle with cold water from a sink faucet and place it into the pile of grass clippings. Does the water in this bottle become warm after a couple of hours?

Is there a minimum amount of grass clippings that are needed to make enough heat to heat the water in a two-liter plastic bottle? To find out, surround a two-liter plastic bottle filled with water with just enough grass clippings to cover it. Does the water become warm after twenty-four hours?
[/am4show]

Do Plants Store Energy?

Friday October 28, 2011

A peanut is not a nut, but actually a seed. In addition to containing protein, a peanut is rich in fats and carbohydrates. Fats and carbohydrates are the major sources of energy for plants and animals.

The energy contained in the peanut actually came from the sun. Green plants absorb solar energy and use it in photosynthesis. During photosynthesis, carbon dioxide and water are combined to make glucose. Glucose is a simple sugar that is a type of carbohydrate. Oxygen gas is also made during photosynthesis.

The glucose made during photosynthesis is used by plants to make other important chemical substances needed for living and growing. Some of the chemical substances made from glucose include fats, carbohydrates (such as various sugars, starch, and cellulose), and proteins.

Photosynthesis is the way in which green plants make their food, and ultimately, all the food available on earth. All animals and nongreen plants (such as fungi and bacteria) depend on the stored energy of green plants to live. Photosynthesis is the most important way animals obtain energy from the sun.

Oil squeezed from nuts and seeds is a potential source of fuel. In some parts of the world, oil squeezed from seeds-particularly sunflower seeds-is burned as a motor fuel in some farm equipment. In the United States, some people have modified diesel cars and trucks to run on vegetable oils.

Fuels from vegetable oils are particularly attractive because, unlike fossil fuels, these fuels are renewable. They come from plants that can be grown in a reasonable amount of time.
[am4show have=’p8;p9;p22;p49;p70;p75;p84;’ guest_error=’Guest error message’ user_error=’User error message’ ]
Materials

Shelled peanut
Small pair of pliers
Match or lighter
Sink

Download Student Worksheet & Exercises

Procedure

ASK AN ADULT TO HELP YOU WITH THIS EXPERIMENT. DO NOT DO THIS EXPERIMENT BY YOURSELF. The fuel from the peanut can flare up and burn for a longer time than expected.

Close the drain in the kitchen sink. Fill the sink with water until the bottom of the sink is just covered.

Using a small pair of pliers, hold the peanut over the sink containing water. Ask an adult to hold the flame of a lit match or lighter directly under the peanut. When the peanut starts to burn, the lit match or lighter can be removed.

Allow the peanut to burn for one minute. MAKE SURE AN ADULT REMAINS PRESENT AND MAKE SURE TO HOLD THE PEANUT OVER THE SINK. To extinguish the burning peanut, drop it into the water. After you have extinguished the peanut, allow it to cool and then examine it carefully.

Observations

How long does it take for the peanut to start to burn? Does the peanut burn with a clean flame or a sooty flame? What color is the flame? What color does the peanut turn when it burns? Did the size of the peanut change after it has burned for several minutes?

Discussion

You should find that the peanut ignites and burns after a lit match or lighter is held under it for a few seconds. Although you only let the peanut burn for one minute as a safety measure, the peanut would burn for many minutes.

In this experiment, when the peanut burns, the stored energy in the fats and carbohydrates of the peanut is released as heat and light. When you eat peanuts, the stored energy in the fats and carbohydrates of the peanut is used to fuel your body.

Other Things to Try

Hold one end of a piece of uncooked spaghetti in a pair of pliers. Ask an adult to hold the flame of a lit match or lighter under the other end of the spaghetti. When the spaghetti starts to burn, place it in an aluminum pie pan that is in the sink. Make sure to extinguish the burning spaghetti with water when you are finished with the experiment. How does the burning of the spaghetti compare with the burning of the peanut?

Exercises

What is the process called where plants get food from the sun?
1. Osteoporosis
2. Photosynthesis
3. Chlorophyll
4. Metamorphosis
Where does all life on the planet get its food?
List two ways that we could use the energy in a peanut:

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Cartesian Diver

Sunday October 23, 2011

Rene Descartes (1596-1650) was a French scientist and mathematician who used this same experiment show people about buoyancy. By squeezing the bottle, the test tube (diver) sinks and when released, the test tube surfaces. You can add hooks, rocks, and more to your set up to make this into a buoyancy game!
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The test tube sinks because the when you squeeze the bottle, you increase the pressure of the water and this forces water up into the test tube, which then compresses the air inside the tube. When this happens, it adds enough mass to cause it to sink. Releasing the squeeze on the bottle means that you decrease the pressure and the water is forced back out of the tube.

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Can a Fuel be Made From Plant Material?

Sunday October 23, 2011

Yeast is a simple living organism that can break down sugars into ethyl alcohol (ethanol) and carbon dioxide. The process by which yeast breaks down sugars into ethyl alcohol and carbon dioxide is called fermentation.

The tiny gas bubbles rising in the liquid mixture in the bottle are carbon dioxide gas bubbles that are made during the fermentation. The balloon on the bottle expands and becomes inflated because it traps the carbon dioxide gas being produced.

The ethyl alcohol that is made during fermentation stays in the liquid mixture. When fermentation is finished, the liquid mixture usually contains about 13 percent ethyl alcohol. The rest of the liquid is mostly water.

The ethyl alcohol can be concentrated by a process called distillation. During distillation, the liquid fermentation mixture is heated to change the ethyl alcohol and some of the water into a vapor. The vapor is then cooled to change it back into a liquid. This distilled liquid contains 95 percent ethyl alcohol and 5 percent water. The remaining water can be removed by special distillation methods to give pure ethyl alcohol.

In some areas of the United States, ethyl alcohol is blended with gasoline to make a motor fuel known as gasohol. About 8 percent of the gasoline sold in the United States is gasohol.

Gasohol burns more cleanly than pure gasoline. This results in fewer pollutants being released into the air. The use of gasohol as a motor fuel is particularly important in cities that have a lot of smog.

Corn syrup is a mixture of simple and complex sugars and water. It is made by breaking down the starch in corn into sugars. The process is called digestion. In this experiment you changed the sugars in corn syrup using yeast. Much of the ethyl alcohol used to prepare gasohol is made by fermenting corn and corn sugar.

Over one billion gallons of ethyl alcohol are made each year by fermentation of sugars from grains such as corn. Ethyl alcohol is a renewable energy source when it is made by fermenting grains such as corn. This is because the grains, such as corn, are easily grown.

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Materials

One package of yeast
Balloon
Water
Measuring spoons
Corn syrup
Measuring cup
Empty, two-liter plastic drink bottle
Funnel (optional)
Sink or bucket

Procedure

Remove the paper label from around an empty, two-liter, plastic drink bottle. Add two cups of water and one package of yeast to the bottle. Swirl the bottle to mix the water and yeast.

Next, add one-quarter cup of corn syrup to the bottle. You may want to use a small funnel to help you add the corn syrup to the bottle. Swirl the bottle to mix the contents.

Place a deflated balloon over the neck of the bottle. Make sure the balloon fits securely over the neck. Place the bottle in a sink or bucket. Check the bottle and balloon after two hours, and then again after four hours. Finally, check the bottle and balloon after twenty-four hours.

When you have finished with the experiment, pour the contents of the bottle down the sink. Then rinse the bottle and sink with water.

Observations

What color is the yeast mixture? Does the balloon start to inflate after an hour or two? Can you see gas bubbles rising to the surface of the yeast mixture? Does the balloon grow larger with time?

Discussion

You should find that soon after you mix together the yeast, water, and corn syrup, changes start to take place in the bottle. You should notice that a foam forms on top of the liquid mixture. You should also see tiny gas bubbles rising to the surface of the liquid. Also, you should notice that the balloon begins to inflate and become large.

Other Things to Try

Repeat this experiment using one tablespoon of table sugar instead of corn syrup. You should find that yeast can also ferment table sugar into ethyl alcohol and carbon dioxide. Table sugar is made from sugar cane and sugar beets. Since sugar cane and sugar beets are renewable plants, ethyl alcohol made from fermenting sugar from these plant products is another renewable energy source.

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Water Cycle Column: Is Rain Pure?

Friday October 21, 2011

When birds and animals drink from lakes, rivers, and ponds, how pure it is? Are they really getting the water they need, or are they getting something else with the water?

This is a great experiment to see how water moves through natural systems. We’ll explore how water and the atmosphere are both polluted and purified, and we’ll investigate how plants and soil help with both of these. We’ll be taking advantage of capillary action by using a wick to move the water from the lower aquarium chamber into the upper soil chamber, where it will both evaporate and transpire (evaporate from the leaves of plants) and rise until it hits a cold front and condenses into rain, which falls into your collection bucket for further analysis.

Sound complicated? It really isn’t, and the best part is that it not only uses parts from your recycling bin but also takes ten minutes to make.

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Here’s what you need:

three 2-liter soda bottles, empty and clean
razor with adult help
scissors
tape
ruler
60 cm heavy cotton string
soil
water
ice
plants
drill and drill bits
fast-growing plant seeds (radish, grass, turnips, Chinese cabbage, moss, etc.)

Here’s what you do:

Download Student Worksheet & Exercises

Make sure your wicks are thoroughly soaked before adding the soil and plants! You can either add ice cubes to the top chamber or fill it carefully with water and freeze the whole thing solid. If you’re growing plants from seeds, leave the top chamber off until they have sprouted.

You can add a strip of pH paper both inside and outside your soil chamber to test the difference in pH as you introduce different conditions. You can check out the Chemical Matrix Experiment and the Acid-Base Experiment also!) What happens if you light a match, blow it out, and then drop it in the soil chamber? (Hint – you’ve just made acid rain!)

Do you think salt travels with the water? What if you add salt to the aquarium chamber? Will it rain salty water? You can place a bit of moss in the collection bucket to indicate how pure the water is (don’t drink it – that’s never a good idea).

Exercises

Do you think salt travels with the water?
What if you add salt to the aquarium chamber? Will it rain salty water?
What happens if you light a match, blow it out, and then drop it in the soil chamber? (Hint – you’ve just made acid rain!)

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Terraqua Column

Friday October 21, 2011

How does salt affect plant growth, like when we use salt to de-ice snowy winter roads? How does adding fertilizer to the soil help or hurt the plants? What type of soil best purifies the water? All these questions and more can be answered by building a terrarium-aquarium system to discover how these systems are connected together.

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Here’s what you need:

two 2-liter soda bottles, empty and clean
two bottle caps
scissors and razor with adult help
tape
water, soil, and plants

Here’s what you do:

Download Student Worksheet & Exercises

Water drips off the roof of your house, down your driveway, over your toothbrush and down the sink, through farm fields, and into rivers, lakes and oceans. While traveling, this water picks up litter, nutrients, salts, oil, and also gets purified by running through soil. All of this has an affect on fish and animals that live in the oceans. The question is, how does it affect the marine ecosystem? That’s what this experiment will help you discover.

Land and aquatic plants are excellent indicators of changes in your terraqua system. By using fast-germinating plats, you’ll see the changes in a relatively short about of time. You can also try grass seeds (lawn mixes are good, too), as well as radishes and beans. Pick seeds that have a life cycle of less than 45 days.

How to Care for your TAC (Terra-Aqua Column) EcoSystem:

Keep the TAC out of direct sunlight.
Keep your cotton ball very wet using only distilled water. Your plants and triops are very sensitive to the kind of water you use.
Feed your triops once they hatch (see below for instructions)
Keep an eye on plant and algae growth (see below for tips)

About the plants and animals in your TAC:

Carnivorous plans are easy to grow in your TAC, as they prefer warm, boggy conditions, so here are a few tips: keep the TAC out of direct sunlight but in a well-lit room. Water should condense on the sides of the column, but if lots of black algae start growing on the soil and leaves, poke more air holes! Water your soil with distilled water, or you will burn the roots of your carnivorous plants. Trim your plants if they crowd your TAC.
If you run out of fruit flies, place a few slices of banana or melon in an aluminum cup or milk jig lid at the bottom of a soda bottle (which has the top half cut off). Invert the top half and place it upside down into the bottom part so it looks like a funnel and seal with tape so the flies can’t escape. Make a hole in the cap small enough so only one fly can get through. The speed of a fruit fly’s life cycle (10-14 days) depends on the temperature range (75-80 degrees). Transfer the flies to your TAC. If you have too many fruit flies, discard the fruit by putting it outside (away from your trash cans) or flush it down the toilet.
You can’t feed a praying mantis too much, and they must have water at all times. You can place 2-3 baby mantises in a TAC at one time with the fruit flies breeding below. When a mantis molts, it can get eaten by live crickets, so don’t feed if you see it begin to molt. When you see wings develop, they are done fully mature. Adult mantises will need crickets, houseflies, and roaches in addition to fruit flies.
Baby triops will hatch in your TAC aquarium. The first day they do not need food. Crush a green and brown pellet and mix together. Feed your triop half of this mixture on the 2^nd and the other half on the 4^th day (no food on day 3). After a week, feed one pellet per day, alternating between green and brown pellets. You can also feed them shredded carrot or brine shrimp to grow them larger. If you need to add water (or if the water is too muddy), you can replace half the water with fresh, room temperature distilled water. You can add glowing beads when your triop is 5 days old so you can see them swimming at night (poke these through the access hole).

Exercises

What three things do plants need to survive?
What two things do animals need to survive?
Does salt affect plants? How?

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Consuming Oxygen

Tuesday October 18, 2011

This experiment not only explains how your body uses oxygen, but it is also an experiment in air pressure circles – bonus! You will be putting a dime in a tart pan that has a bit of water in it. Then you will put a lit candle next to the dime and put a glass over the candle with the glass’s edge on the dime. Once all of the air inside the glass is used up by the candle, the dime will be easy to pick up without even getting your fingers wet! Ready to give it a try?

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Here’s what you need

- 1 aluminum tart pan
- 1 votive candle
- 1 box of matches
- 1 clear drinking glass, 12 or 16 oz.
- 1 dime
- water
- 1 pair of goggles
- Adult supervision!

Download Student Worksheet & Exercises

Here’s what you do

Pour about ¼ inch of water in the pan and place the dime right in the middle.
Position the candle next to the dime and ask an adult to light it for you
Put the drinking glass over the candle with its edge resting on the dime. Watch closely to observe what happens.
Once the water is inside the glass, you can carefully remove the dime from under its edge. If done properly, the water will stay in the glass.

What’s going on?

When you put the glass over the candle, you created a closed system. The candle only had the gas trapped inside the air beneath the glass to burn. As the candle burned, the gases in the glass burned as well. They were transformed from a state of gas to a very compact solid state that stuck to the wick of the candle (this is why the wick gets black when a candle burns).

An important thing to note is that as the air was removed, the pressure inside the glass was reduces. Lower air pressure inside your closed system created an imbalance with the regular air pressure on the outside of the glass. Since there was more pressure on the outside, the water was pushed inside the glass. The dime helped to make a gateway for the water to be more easily pushed into the glass.

This lab serves to illustrate that oxygen is consumable. It’s the same thing that happens inside your body, but at a much slower rate that what you witnessed with the candle. Your lungs contain about 1,490 miles (2,400 km) of air passages to help absorb oxygen. If they could be spread out flat, an average set of lungs have a surface area of approximately 650 square feet. The sheer size of this system gives you the chance to absorb all the oxygen that your body needs.

Exercises

What do we mean when we say that oxygen is consumable?
What is the difference between an open and a closed system?
Where is the higher pressure in this experiment?
Why does water rise inside the glass?

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Make an Insect Aspirator

Monday October 17, 2011

Some insects are just too small! Even if we try to carefully pick them up with forceps, they either escape or are crushed. What to do?

Answer: Make an insect aspirator! An insect aspirator is a simple tool scientists use to collect bugs and insects that are too small to be picked up manually. Basically it’s a mini bug vacuum!

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Download Student Worksheet & Exercises

Here’s what we’ll need:

A small vial or test tube with a (snug fitting) two-holed rubber stopper.
Two short pieces of stiff plastic tubing. We’ll call them tube A and tube B.
Fine wire mesh (very small holes because this is what will stop the bugs from going into your mouth!)
A cotton ball.
One to two feet of flexible rubber tubing.
Duct tape or a rubber band.

Here’s how we make it:

Insert the tube A and Tube B into the stopper such that the stopper is in the middle of both pieces.
Bend both A and B plastic tubing 90 degrees away from each other. Their ends should be pointing away from each other.
Cut a square of mesh large enough to the end of the plastic tubing. Tape (or rubber-band) the mesh over bottom of tube A only. Remember, if you cover both of the tubes the bugs won’t be able to enter the aspirator.
Insert a small amount of cotton ball into the other side of tube A (not enough to block airflow, just enough to help filter the dust and particles entering the vial.
Cut another piece of mesh and cover the other end of Tube A. Secure that mesh with another piece of tape/rubber band.
Fit the rubber tubing over the top of tube B (the bent side).
Fit the stopper into the vial/test tube.

How it works: To use the aspirator, hold the end of the rubber tubing near the insects you want to collect, and suck through the top of tube A. The vacuum you create sucks the insects into the vial/test tub (make sure they can fit in the tube!).

Troubleshooting: The bugs aren’t being pulled into the vial! In that case the suction may not be strong enough. Remove the cotton ball and try again. If it still is not working check to make sure the aspirator is air-tight (is the stopper fitting snuggly into the vial? Are there cracks/holes around or in the plastic tubes?).

TIP: I kept eating bugs! Make sure your wire mesh is very fine (the holes are smaller than the bugs you’re trying to collect). Otherwise you may be ordering a lunch you don’t want!

Exercises

Why don’t we use a large vacuum to suck up the bugs?
Why do we need a small mesh covering on the end of the straw that we suck on?
Why do we need to be careful about catching ants?
What insects did you catch that you rarely see?
What familiar insects did you catch? (answers may vary).

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Berlese funnel

Monday October 17, 2011

Unsurprisingly, often the most interesting critters found in soil are the hardest to find! They’re small, fast, and used to avoiding things that search for them. So, how do we find and study these tiny insects? With a Berlese Funnel (Also called the Tullgren funnel)!

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The funnel separates the insects from the soil with heat. A light bulb heats the soil at one end of a funnel and causes the insects to migrate, through mesh, to a preservative liquid at the other end of the funnel. Originally Antonio Berlese used a hot water bottle to provide the heat. Later, Albert Tullgren modified the funnel to work with a light bulb. Thus, we now call it the Berlese Funnel, the Tullgren Funnel, or the Berlese-Tullgren Funnel.

Download Student Worksheet & Exercises

An ultraviolet lamp used to attract night flying insects. The simplest set up is to hang a white sheet on a line and hang a portable black light on one side of the sheet. Insects will land on the sheet and can be tallied, identified or collected.

To make a larger, more permanent model, here’s what you need:

1 gallon tractor funnel.
Clothespins.
A light fixture that fits on top of the funnel and has a reflective interior.
A bucket that has a smaller diameter than the top of the funnel. The funnel needs to be suspended from the bucket so the insects can fall into the jar.
A clean jam-jar.
Rubbing alcohol.
¼ inch wire mesh.
Light bulb. The wattage has to be high enough to heat the soil, but not so high that it will light the funnel on fire. Best to do it by trial and error with lots of supervision.
Soil. The best will be from a compost pile.

Here’s how you make the funnel:

Cut a large hole in the side of the bucket. This will allow you to retrieve the jar without disassembling the apparatus. Naturally, the hole should be larger than the jar.
Fit the wire mesh so that it covers the bottom third of the funnel.
Fit the funnel on top of the bucket.
Fit the light fixture (with the light bulb in it) on top of the funnel with the clothespin.
Place the jar underneath the funnel (with or without the rubbing alcohol depending on if you want the specimens dead or alive).

How to use the funnel: Simply turn on the light and wait. Check the vial every fifteen minutes or so for an hour. After you have finished remember to turn off the light! Also, remember that some of the specimens may be very small and best observed under a microscope. For the best results do it in the morning or on a cold day.

How the funnel works: Figure 1 shows the funnel in action. The light (G) creates heat. The insects in the soil don’t like heat, so they move from the soil (D) through the funnel (C) into the jar (B). The jar is filled with rubbing alcohol (A) preserves the specimens. The wire (not shown in the figure) keeps most of the soil from falling into the jar.

Troubleshooting: What if there still aren’t any bugs after an hour? If this happens, don’t panic. Ask yourself these questions:

Is the light strong enough? If the light is not strong enough (i.e. generating enough heat), then the soil will not get hot enough to push the insects into the jar. The funnel works by creating a gradient of heat which the bugs move down into the jar. If the light isn’t creating that gradient, no critters will feel like moving.
Is it hot today? If the sun is out and making everything hot, then the light will not make enough of a difference in heat—there will not be a heat gradient to move down. If so, don’t worry; just try again the next morning.
Is there a problem with the funnel? Is the nozzle of the funnel too far from the mouth of the jar? Make sure that the specimens are falling into the jar and not around it. Is the mesh wire too fine? You want mesh that will keep most of the soil in the funnel, but not so fine that it will stop the bugs from getting through.
Lastly, are there any bugs in the soil? Not just any dirt will do for this project. You need soil rich with life! The best place to find this type of soil is near/in a compost pile (after it has become soil).

Exercises

Why are some insects difficult to find in soil?
Why does the Berlese Funnel work to find insects?
What if the insects do not respond to the heat lamp in your experiment?
What types of insects were you able to find using the Funnel?

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Make a Waterscope

Monday October 17, 2011

As you walk around your neighborhood, you probably see many other people, as well as some birds flying around, maybe some fish swimming down a local stream, and perhaps even a lizard darting behind a bush or a frog sitting contently on top of a pond. Most likely, you know that all of these living things are animals, but they are even more closely related than that.

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Tide pools are best observed undisturbed. But, they’re too shallow to snorkel… So how to can we explore them without removing their inhabitants? With an Aquascope! Aquascopes are very cheap and easy to make. With only a coffee can, some plastic food rap, and a couple of other items you can make a window into the world of tide-pools! In principle, aquascopes allow us to take a glass-bottom-boat tour of the rich ecosystems of tide pools. The plastic acts as the glass, while the coffee can allows us to break the distorting surface of the water.

Here’s a video to get you started:

Download Student Worksheet & Exercises

Here’s what you need:

milk or juice jug
plastic wrap
scissors
rubber band

Here’s the steps to make the waterscope:

Clean out your jug first. Then cut the bottom and top off without cutting off the handle.
Cover the opening at the bottom with your plastic wrap, securing it in place with the rubber band. Use tape if you need extra support to hold the plastic wrap in place. The window needs to be water-tight.
Place the waterscope in the water, bottom-side down. You’ll be able to see all kinds of interesting creatures through your scope!
Try to keep your scope still so the animals won’t be afraid to come close to you so you can have a good peek at their world. The aquascope works the same way snorkel goggles work—except you don’t have to get wet!

Why this works: You can’t see clearly underwater with just your eyes for a couple of reasons. One is the thickness of the lens on your eye, but the main one is the index of refraction of water is different than that of air. Light rays bend when they travel from one medium to another of different density (refer to the Disappearing Beaker experiment for more on this topic). The amount that the light bends depends on refractive index of each substance along with the shape. The eye focuses images on the retina, and our eyes are built for viewing in air. Water has approximately the same refractive index as the cornea which effectively eliminating the cornea’s focusing properties. This is why you see a blurred image underwater. The eyes are focusing the image them far behind the retina instead of on the retina. The waterscope puts a layer of air between your eyes and the water (the same way goggles do) so you can view underwater without blurred vision.

Troubleshooting: The key to the aquascope is the taught plastic wrap. If it’s loose, or if there are holes, it won’t work as well. Make sure that the plastic wrap is securely fastened to the can, and is stretched tight. If you find your waterscope leaks, use a stronger rubber band to secure your plastic wrap in place. You can alternatively use strong waterproof tape or hot glue to secure it in place, but use the rubber band first so you can stretch the film tightly over the open end.

Exercises

What is the term for light rays bending?
Why is underwater vision blurred?
How can we focus vision underwater?

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Predator-Prey: Who Eats Whom?

Sunday October 16, 2011

The way animals and plants behave is so complicated because it not only depends on climate, water availability, competition for resources, nutrients available, and disease presence but also having the patience and ability to study them close-up.

We’re going to build an eco-system where you’ll farm prey stock for the predators so you’ll be able to view their behavior. You’ll also get a chance to watch both of them feed, hatch, molt, and more! You’ll observe closely the two different organisms and learn all about the way they live, eat, and are eaten.

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This experiment comes in two parts. The materials you need for both parts are:

four 2-liter soda bottles, empty and clean
2 bottle caps
one plastic lid that fits inside the soda bottle
small piece of fruit to feed fruit flies
aluminum foil
plastic container with a snap-lid (like an M&M container or film can)
scissors and razor with adult help
tape
ruler
predators: spiders OR praying mantis OR carnivorous plants (if you’re using carnivorous plants, make sure you do this Carnivorous Greenhouse experiment first so you know how to grow them successfully)
soil, twigs, small plants

Fruit Fly Trap

In order to build this experiment, you first need prey. We’re going to make a fruit fly trap to start your prey farm, and once this is established, then you can build the predator column. Here’s what you need to do to build the prey farm:

Download Student Worksheet & Exercises

Did you know that fruit flies don’t really eat fruit? They actually eat the yeast that growing on the fruit. Fruit flies actually bring the yeast with them on the pads of their feet and spread the yeast to the fruit so that they can eat it. You can tell if a fruit fly has been on your fuit because yeast has begun to spread on the skin.

When you have enough fruit flies to transfer to the predator-prey column, put the entire fruit fly trap in the refrigerator for a half hour to slow the flies down so you can move them.

If you find you’ve got way too many fruit flies, you might want to trap them instead of breed them. Remove the foil buckets every 4-7 days or when you see larvae on the fruit, and replace with fresh ones and toss the fruit away. Don’t toss the larvae in the trash, or you’ll never get rid of them from your trash area! Put them down the drain with plenty of water.

Predator-Prey Column

You can use carnivorous plants, small spiders, or praying mantises. If you use plants, choose venus flytraps, sundews, or butterworts and make sure your soil is boggy and acidic. You can add a bit of activated charcoal to the soil if you need to change the pH. Since the plants like warm, humid environments, keep the soil moist enough for water to fog up the inside on a regular basis. You know you’ve got too much moisture inside if you find algae on the plants and dirt. (If this happens, poke a couple of air holes.) Don’t forget to only use distilled water for the carnivorous plants!

Keep the column out of direct sunlight so you don’t cook your plants and animals.

Exercises

What shape is the head of the mantis?
How many eyes does a praying mantis have?
How else has the mantis head evolved to stalk their prey?
How does a praying mantis hold its food?
Do fruit flies eat fruit?
How do predators and prey change over time?

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Eco-Column

Sunday October 16, 2011

What grows in the corner of your windowsill? In the cracks in the sidewalk? Under the front steps? In the gutter at the bottom of the driveway? Specifically, how doe these animals build their homes and how much space do they need? What do they eat? Where do fish get their food? How do ants find their next meal?

These are hard questions to answer if you don’t have a chance to observe these animals up-close. By building an eco-system, you’ll get to observe and investigate the habits and behaviors of your favorite animals. This column will have an aquarium section, a decomposition chamber with fruit flies or worms, and a predator chamber, with water that flows through all sections. This is a great way to see how the water cycle, insects, plants, soil, and marine animals all work together and interact.

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Here’s what you need:

four (or more) 2-liter soda bottles, empty and clean and with caps
scissors
tape
razor with adult help
ruler
soil
water
plants or seeds
compost or organic/food scraps
spiders, snails, fruit flies, etc

Here’s what you do:

Download Student Worksheet & Exercises

You can easily incorporate the Water Cycle Column, the Terraqua Column, the Predator-Prey Column, Worm Column, and the Fruit Fly Trap into your Eco-Column. If you want to make your Eco-Column more permanent, seal it together with silicone sealant, making sure you have enough drainage holes and air holes in the right places first.

Exercises

What are parts of the eco system?

Give an example of each.

What do decomposers do?

How do fruit flies breed?

How does the precipitation funnel function in this eco column?

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Special Science Teleclass: Renewable & Alternative Energy

Sunday October 2, 2011

This is a recording of a recent live teleclass I did with thousands of kids from all over the world. I’ve included it here so you can participate and learn!

Discover the world of clean, renewable energy that scientists are developing today! Explore how they are harnessing the energy of tides and waves, lean how cars can run on just sunlight and water, tour a hydroelectric power plant, visit the largest wind farms on the planet, and more! You’ll learn how streets are being designed to generate electricity, how teenagers are making jet fuel from pond scum in their garage, and how 70 million tons of salt can provide free, clean energy 24 hours a day forever! During class, you’ll learn how to bake solar cookies, magni-fry marshmallows and do the experiment with light Einstein won a Nobel prize for that is the basis of all photovoltaic energy today.

Materials:

One cup each: hot (not boiling), cold, and room temperature water
Cardboard box, shoebox size or larger.
Aluminum foil
Plastic wrap (like Saran wrap or Cling wrap)
Hot glue, razor, scissors, tape
Wooden skewers (BBQ-style)
Black construction paper
Cookie dough (your favorite kind!)
Chocolate, large marshmallows, & graham crackers if you want to make s’mores! If not, try just the large marshmallow.
Large page magnifier (also called a Fresnel lens, found at drug stores or places that also sell reading glasses, or at Amazon.com)

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What’s Going On?

For the main experiment:

The Fresnel (“FRAY-nell”) lens is a lot like a magnifying glass. Convex lenses (like a handheld magnifier) are thicker in the middle – you can actually feel it with your fingers. A Fresnel lens was first used in the 1800s to focus the beam in a lighthouse. It has lots of ridges you can feel with your fingers. It’s basically a series of magnifying lenses stacked together in rings (like in a tree trunk) to magnify an image.

The Fresnel lens in this project is focusing the incoming sunlight much more powerfully than a regular hand held magnifier. But focusing the light is only part of the story with your roaster. The other part is how your food cooks as the light hits it. If your food is light-colored, it’s going to cook slower than darker (or charred) food. Notice how the burnt spots on your food heat up more quickly!

The best thing about Fresnel lenses is that they are lightweight, so they can be very large (which is why light houses used these designs). Fresnel lenses curve to keep the focus at the same point, no matter close your light source is.

Questions to Ask

What other kinds of food can you roast with your setup?
Does a white marshmallow or chocolate-covered marshmallow cook faster? Why?
Does it matter what angle you point your roaster at?
Will it work with an indoor light?
Why do you need the foil? Can you skip it?
Do we have to use a Fresnel lens? What about a handheld magnifier – would that work?

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Worms!

Thursday September 29, 2011

Here we’re going to discuss the differences between three types of worms; flatworms, roundworms, and segmented worms. The word “worm” is not, in fact, a scientific name. It’s an informal way of classifying animals with long bodies and no appendages (no including snakes). They are bilaterally symmetrical (the right and left sides mirror each other). Worms live in salt and fresh water, on land, and inside other organisms as parasites.

The differences between the three types of worms we will discuss depend on the possession of a body cavity and segments. Flatworms have neither a body cavity nor segments. Roundworms only have a body cavity, and segmented worms have both a body cavity and segments.

Flatworms (Phylum Platyhelminthes) have incomplete digestive systems. That means that their digestive system has only one opening. The gas exchange occurs on the surface of their bodies. There are no blood vessels or nervous systems in flatworms. Some are non-parasitic, like the Sea flat worm, and some are parasitic, like the tapeworm.

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Roundworms (Phylum Nematoda) have body cavities—as contrasted with flatworms which do not. The body cavity allows roundworms to have complete digestive tracts (both a mouth and an anus). The mouth and anus are connected by a gut—where the food is digested. They also have a simple nervous system and brain.
Roundworms can be parasites of plants and animals. In dogs they are often know to cause heart problems. In humans roundworm parasites can sometimes cause a swelling disease called elephantitis.

Annelids or Segmented Worms (Phylum Annalida) the most developed of the three, have both a body cavity and segments. Their body cavity helps give them structure—it serves as a hydroskeleton. By “segmented” it’s meant that they are divided into repeating units. They can be non-parasitic (i.e. earthworms) or parasitic (i.e. leeches). Interestingly, the giant red leech only eats giant earthworms.

Worm Column

If you’re fascinated by worms but frustrated that you can’t see them do their work underground, then this worm column is just the ticket for you. By using scrap materials from the recycling bin, you’ll be able to create a transparent worm farm. here’s what you need:

two 2-liter soda bottles, empty and clean
one brown paper grocery bag
20 red worms
newspaper, old leaves, peat moss, and/or straw for worm bedding
last night’s dinner, organic scraps, plant material for worm food

Here’s what you do:

Download Student Worksheet & Exercises

Things to Compare with your Worms:

Look at the worms under the magnifying glass.
Measure the lengths of the worms.
Make note of:
1. The outer layer of the worms: Is it hard? Is it segmented? What are other observations that can be made?
2. Do they have legs?
3. Do they have antenna?
4. What are the main differences?
5. What are the main similarities?

Garden Worm Tower

Here’s how you can make your own worm tower right in your garden:

Build your own worm farm and watch them turn food scraps into soil!

Materials:

2 polystyrene boxes with lids the same size. (Let’s call them Bin A and Bin B.)
A sheet of insect screen to fit the bottom of the boxes
Newspaper clippings
Garden soil
Food scraps (half-eaten fruits and veggies, stale biscuits and cakes, crushed egg shells, coffee grounds)
Water
Worms (Either “Tiger”, “reds”, or “blues”; ask for them at your local garden store)

Build the farm:

Punch evenly spaced holes in the bottom of Bin A.
Place the insect screen on the bottom of Bin A (this is so that the worms don’t fall out).
Fill Bin A ¾ full with wet newspaper clippings.
Add a layer of garden soil to Bin A.
Add the worms.
Place Bin A in Bin B. Make sure there’s enough room in Bin B when Bin A’s placed in it to collect the worm pee and waste. Be sure to empty and clean Bin B every couple days.
Add food to bin A! Start off small. You don’t want to over-feed the worms. Start out with a couple scraps in the corner and see how long it takes for them to disappear—that should give you a good idea of how much to feed your worms.

Earthworm Dissection

You can dissect a earthworm right at home using this inexpensive earthworm specimen and simple dissection tools!

Exercises

What are three types of worms?
What are the characteristics of each?
What are the elements of a complete digestive system?
What are some benefits of worms in gardening?

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Butterfly Life Cycle

Wednesday September 28, 2011

Insects are not only the most diverse subgroup of arthropods, but with over a million discovered species it is the most diverse group of animals on earth. Although they can’t all be as beautiful as a butterfly, they all play important roles in their ecosystems—just think of where we would be without bees!

The segmented exoskeletons of insects have a hard, inner layer called the cuticle, and a water-resistant outside layer called the exocuticle. Insects are divided into two major groups: winged insects and wingless insects. Air is taken in through structures called spirials, and delivered directly to the body.

Most insects reproduce sexually and are oviparous (hatch from eggs after the eggs are laid), although some insects reproduce asexually.

You can grow your own butterflies using a premade kit from Home Training Tools!

Biological Nets

Wednesday September 21, 2011

A biological net is one of the essential tools of a field biology researcher — you! A bio-net allows you to safely and gently gather samples. Whether you’re studying butterflies or tadpoles a bio-net is the tool to have! Important safety note: Do both of these with parental supervision. Many of the steps are tricky and involve sharp objects.

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What you need (these materials are not listed int he main shopping list, as this project is a little more involved):

1-meter x 2-meter fly-wire screen netting (gauge = 0.6mm spaces)
4 strips (20cm x 1m) of heavy canvas
2 broom handles
Nails
Thread
Hammer
Sewing machine
Ironing board with iron

How to make a two-handled bio-net:

Basically, you’re going to create a square net of fly-wire, frame it with the strips of canvas, then attach the broom handles to either side. Your final product should look like this:

Fold the fly-wire in half so it’s 1m X 1m.
Fold the edges of the canvas strips under so there’s a smooth edge to each of the sides of the strips. About 1cm each side should work.
Sew two of the strips to the top and bottom of the fly-wire square.
Sew the other two to the sides of the fly-wire, but leave enough space for the broom handles to slip in.
Slip the broom handles into the sleeves you just created. Use the nails to firmly attach the canvas sleeves to the handles. These are the handles of the bio-net. Voilà!

How to make a single handled sampling net:

What you need:

4 (60cm X 30cm) pieces of fly-wire netting (250um mesh)
1.5m piece of bias tape
1m (or longer) broom handle
Thread
Scissors
Sewing machine
3 wire coat hangers
Drill with 0.5com wood bit
Pliers
Binding

Let’s make the net!

Cut the netting into four triangles (50cm high with 30cm bases) (1).
Sew them together into a single net.
Sew a 1.5m strip of bias tape onto the net. Don’t sew both sides. Leave the outside flap un-sewn so that you can sip the wire in (2).
Drill a hole in one of the ends of the broom handle.
Remove the hooks from the hangers.
Untwist the hangers and slip into the bias-tape sleeve.
Sew the bias tape sleeve closed.
Twist the tops of the hangers together into a stem and insert into the hole in the broom handle.
Bend the hanger hooks into a “U” and use it to bind the net to the handle.
Bind the U to the broom with the binding (5).

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Raising Orange Spotted Roaches

Thursday September 1, 2011

When you hear “roach” you might not immediately think of something that would make a good pet, but not all roaches are like the cockroaches you might have seen in your house!

Species such as the Orange Spotted Roach (Blaptica dubia) make excellent insect pets: they don’t cost much, they have an interesting life cycle and habits, and they do not require much effort to care for. Their average lifespan is about 18 months and you’ll be able to learn more about their fascinating life cycle (from egg to adult) if you allow them to breed!

A pet roach isn’t a pest?

It may seem like all roaches are pests, but of 4,000 species, only 4 or 5 live in homes and are considered pests (such as the American cockroach). Most roaches live in tropical environments far from domesticated areas. They are very different from the kind of household pest you might think of when you hear “roach.”

You might think roaches would make pretty boring pets, but they are surprisingly fast and fun to watch. You can learn a lot about insect anatomy and what makes roaches unique by taking care of them. The species that make good pets do not smell, are not noisy, cannot fly, and generally are very easy to clean up after. They typically are most active at night, because they prefer a dark environment like they have on the floor of the rainforest. They love to hide during the day, but will come out to eat.

Can I touch them? They are meant to be pets, and are perfectly safe to handle. A good environment for roaches is a small aquarium or plastic cage with cardboard egg cartons for them to hang out in. You might try picking up one of the egg cartons where a roach is hiding, then either hold the carton so the roach can crawl around on it or let the roach crawl in to your hands. Hold out your hand, keeping your fingers together and flat. Let the roach crawl on you, then slowly lift out your hand and cup it slightly. Remember to wash your hands afterwards, using warm water and soap. Although these insects don’t cause diseases in humans, they may be carrying harmful bacteria, so it is important to wash your hands so that you don’t get sick.

How long do they live? It varies, but species like Orange Spotted Roaches have a lifespan of 18-24 months. The female gives live birth, usually to 20-30 babies at a time. The babies reach maturity in 3-4 months after they are born. While they are growing into adults, they will molt – shedding their outer hard shell, or exoskeleton, and then growing a bigger one.

Will my roaches breed? If you get one male and one female, there is a good chance that they will breed under the right circumstances. If you do not want baby roaches, keep the temperature of the habitat around 70 degrees, or normal room temperature. Adult Orange Spotted Roaches will be fine at this temperature, but they will not mate because their young need higher temperatures to survive. If you would like to see the complete life cycle, you will need to ensure that their habitat has enough heat and humidity.

Feeding Time: What does a pet roach eat? They are omnivores – they eat plants and meat. So a good basic diet contains protein from plants and animals and fiber from grains. You can buy special roach food for them and then to supplement their diet give them fresh fruits and vegetables once a week. Try putting a slice of apple, banana, orange, carrot, potato, or zucchini, or a few spinach leaves in a shallow plastic dish and put it in their habitat. This will provide vitamins and minerals for your pets. Be sure to take the uneaten produce out of the habitat within 48 hours to prevent mold from growing, or attracting ants or fruit flies. A great roach diet would be dry food every day and a fresh food supplement once a week.

Be sure to keep their water dish full. Roaches can live a long time without food, but usually only survive three days without water. The water dish also helps make their habitat more moist and humid. For easiest care, use water absorbent crystals that hold water. You can keep an airtight container of prepared water crystals in a cool place, and add another crystal to the water dish whenever needed (usually every 2-3 days).

If the habitat is hot and humid, the roaches will be more active, which means they will also eat and drink more.

Cleaning Time: You should periodically clean out your pet roach’s habitat to make sure there is no mold growing. Cleaning out the habitat takes only a few minutes and will prevent any bad odors coming from your insects. When is the right time to clean the habitat? When you see small dark roach droppings starting to collect on the bottom, you should clean the habitat out. Usually about once a month is a good time. The minimum should be once every other month.

To clean out the habitat, first remove the roaches. Place them in a container that has smooth sides to prevent them from climbing out. Pick up the roaches one at a time and transfer them to the carton or other container. If a roach is hiding in an egg carton, carefully lift out the carton, then let the roach crawl off into the container or onto your hand. Wash your hands with soap and warm water after touching the roaches.

Take the food and water dishes out, as well as the egg cartons, and place them on paper towels. Rinse the container out and then wash it with a solution of 10 parts warm water to 1 part bleach. Rinse the container again and dry it thoroughly. Place the food and water dishes back in the container. If the cardboard egg cartons seem clean, put them back into the container. Don’t use foam egg cartons. You can also use cardboard tubes in different sizes (mailing tubes, toilet paper tubes, or wrapping paper tubes cut down to shorter lengths) so the roaches can crawl in them. When you’re finished cleaning, throw the used egg cartons away as well as the paper towels. Transfer your roaches back to their habitat, using a flat hand so they can crawl off.

Building a Roach Ranch: If you decide to get a pet roach, you can create a habitat to be as simple or creative as you like. If you wish to make a more natural-looking habitat for your pet roaches to enjoy, you can buy peat moss or coconut husk mulch from a pet store (in the Reptile section). Put in a layer of moss or mulch (about one inch), then add pieces of bark for the roaches to climb on and hide under. This type of Roach Ranch will be similar to the Orange Spotted Roaches’ natural environment in the rainforests of South America.

You can make a Roach Ranch out of cardboard, which can easily be thrown away when it gets dirty. Make a multi-level mansion for your roaches by cutting 3-4 identical shapes (square, rectangle, L-shape) from cardboard. Put separators in between each level – use stacked cardboard strips that are one inch wide and several inches long. Each level should be separated about ½” or three strips of cardboard stacked together. Use Elmer’s glue to attach the separators and flat levels, and let it dry completely (may take up to 24 hours) before putting it in your roach habitat. Add cardboard tubes or crumpled newspaper to complete your Roach Ranch. Remember that it will be easier to clean if roach droppings can fall freely to the ground. When you clean your habitat, check to see if your Roach Ranch is staying clean. Throw away any parts that have been well-used and add new cardboard material for the roaches to climb.

Should I brush my teeth?

Tuesday August 23, 2011

One place where bacteria can be found is on your teeth. This is why it’s so important to brush well. Don’t believe me? Then this experiment is for you. You’ll need to gather your materials and make sure you have a toothbrush and microscope nearby.

This is important because prokaryotes are incredibly common and have a huge impact on our lives. You may already know some of the ways bacteria can be harmful to you, and this is certainly important information. Scientists have used knowledge of prokaryotes to create medications, vaccines, and healthy living habits that have led to a healthier life for billions of people.

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Materials:

water
toothbrush
microscope with coverslips and slides

Experiment:

Place a drop of water on a microscope slide.
Gently brush your toothbrush against your teeth and then apply the saliva from the brush to the slide.
Add a cover slip, and observe under the microscope. Draw what you see.

Here’s a short video on a real bacterial colonization of the mouth after only 8 hours of having a cleaning done at the dentist:

If you’ve ever gone to the store to buy toothpaste, you know there many brands. Do any actually do a better job of getting rid of bacteria on your teeth? This is a great question for the scientific method. Here’s what you do:

Brush your teeth really well.
Swab your teeth with a cotton ball and apply to a petrie dish of agar.The next day, brush with a different brand of toothpaste, and again, swab and apply to a different dish.
Repeat for five days with five different brands. Record the growth of bacteria on each dish for each day.
Remember that “day 1” for the first dish will be different than “day 1” for the second dish, and so on.
Which brand left the fewest bacteria? Could there be factors that caused the difference besides toothpaste brand? (Hint: Do you eat the same thing every day?)

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What Color Light Do Plants Like Best?

Tuesday August 23, 2011

If you’re thinking sunlight, you’re right. Natural light is best for plants for any part of the plant’s life cycle. But what can you offer indoor plants?

In Unit 9 we learned how light contains different colors (wavelengths), and it’s important to understand which wavelengths your indoor plant prefers.

Plants make their food through photosynthesis: the chlorophyll transforms carbon dioxide into food. Three things influence the growth of the plant: the intensity of the light, the time the plant is exposed to light, and the color of the light.

When plants grow in sunlight, they get full intensity and the full spectrum of all wavelengths. However, plants only really use the red and blue wavelengths. Blue light helps the leaves and stems grow (which means more area for photosynthesis) and seedlings start, so fluorescent lights are a good choice, since they are high in blue wavelengths.

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For my fourth grade science project, I placed a box over a plant and poked different colored lights into each upper corner to see which way the plant grew. It turned out that my plant grew toward the blue light the most. When I turned off the red light, my little plant stopped flowering, but started flowering again when the red light turned on.

After doing my homework, I learned that chemicals in my plant respond to light and dark conditions, which means that my little plant could “tell time” by using chemistry. Not the 12-hour clock that we use to tell time with, but they know time over a longer period, like when to flower in a season and when to conserve energy for winter.

I know now that if I had indoor plants, I’d choose fluorescent bulbs high in the blue wavelengths, and I’d also add an incandescent bulb if my plant had flowers I wanted to blossom. Since incandescent also produces heat, I’d also try playing with red LED lights which weren’t available to me when I did my project, but would make an interesting study today!

Here’s a video on what happens if you use a black light with indoor plants:

The scientific method is used by scientists to answer questions and solve problems. Often, good scientific questions are best on things we already know. For example, we know plants need light to grow because the light allows them to make their own food, but what color of light is best? Use the scientific method in the lab below to figure it out.

Experiment:

Place four plants in an area that will get minimal natural lighting.
Do some colors of light help plants grow better than plain white light? Make a hypothesis about this question.
To test things out, grow one plant with plain white light. Grow the other plants with colored light, either by using colored bulbs or by covering white bulbs with tissue paper.
Make daily observations. Which plant grew best? Was your hypothesis correct?

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How to Grow Mushrooms

Tuesday August 23, 2011

If you have ever seen mold growing on an old loaf of bread or eaten a mushroom, you have encountered a fungus. Fungi (that’s the plural of fungus) are a group of organisms, or living things, that are all around us. Mold on bread and mushrooms on pizza are both examples of fungi.

Fungi have an important job. They help break down other material, so that living things are able to grow in soil. This helps make nutritious foods for other organisms. Fungi are needed for life!

Do you think mushrooms are plants? Scientists used to think that all fungi were plants. Now they know that there are some very important different between these two groups of organisms. One of the most important differences is that plants are autotrophic. This means that they can make their own food, just by using the sunlight. Fungi can’t do this. They have to “eat” other living things in order to get the energy they need. This is called being heterotrophic.

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Another difference between plants and fungi is that fungi have cell walls like plants do, but their cell walls are made of chitin. Chitin is a material containing nitrogen that is also found in the shells of animals including beetles and lobsters.

Fungi do not have a vascular system, the system used to transport water and nutrients in plants, but do have hyphae, a structure you will learn about in the next section. Although mold and mushrooms are easy to see, most fungi are a lot harder to see. Some are so small they can only be seen with a microscope.

Others are big enough to see, but live in places that make them hard to find. For example, some fungi live deep in the soil, in decaying logs, inside plants and animals, or even inside or on top of other fungi!

Scientists have estimated that there are 1.5 million species of fungi, and these organisms live all over. Most are found on land, although some do live in water. Some fungi can even live in deserts. No matter their environment, fungi act as decomposers. This means that the fungi break down materials to make their environment better for other organisms to grow.

Humans use fungi for many purposes. One of the most common uses is in food. Mushrooms are eaten by many people on pizza or in salads. But yeast is used in the fermentation process to make beer, wine, and bread.

We’re going to learn how to grow our own mushrooms in this video below. Remember, never eat a mushroom unless you check with an expert first. Poisonous mushrooms look similar to edible ones, so be absolutely certain which kind it is before popping one in your mouth.

NEVER pick wild mushrooms! In addition to the uncertainty in the type of mushroom, there’s also possible harmful bacteria growing on the mushroom.

Fungi are also important in the production of some antibiotics, including penicillin and the chitin in cell walls has been said to have wound healing properties.

Learn more about Kenny and mushrooms from Veggie Gardening Tips!

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Ideas for Exploring Microscopic Life

Tuesday August 23, 2011

Living things are all around us. Sometimes the living things we notice the most are animals, whether its birds chirping in the trees, our pet dogs, or even our fellow human beings. However, most living things are not animals - they include bacteria, archae, fungi, protists, and plants. These organisms are extremely important to learn about. They make life possible for animals, including human beings, by keeping soil ready for growth, and providing oxygen for our survival. No life would be possible without these remarkable organisms.

The prokaryotes, bacteria and archaea represent an amazingly diverse group of organisms only visible when one looks under a microscope. These single-celled organisms obtain energy and reproduce in a variety of ways.

Though some bacteria are harmful, causing disease, many are very helpful, providing the nitrogen we need to live and aiding in digestion. Archaea have been found in some of the most extreme environments on the planets, including environments that are remarkably hot or salty.

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Here are a couple of videos that will give you a few ideas on how to view this amazing world using a compound microscope, UV light, and more. First, we're going to grow our own bacteria, then we'll look how to identify the bacteria already around you.

Grow Your Own Bacteria

Bacteria, both good and bad, are all around. In fact, there are more bacteria in your mouth than people on Earth! See where you can find bacteria in the activity below.

Materials:

petri (petrie) dish
agar
cotton swab
sink or bathtub

Experiment:

1. Prepare your petrie dish of agar.
2. Using your cotton ball, swab a certain area of your house. (Think about what areas might have a lot of bacteria.)
3. Rub the swab over the agar with a few gentle strokes before putting the lid back on and sealing the petrie dish.
4. Allow the dish to sit in a warm area for 2 or 3 days.
5. Check the growth of the bacteria each day by making a drawing and describing the changes.
6. Try repeating the process with a new petrie dish and a swab from under your finger nails or between your toes.
7. Throw away the bacteria by wrapping up the petrie dish in old newspaper and placing in the trash. (Don't open the lid.)

What's happening?

The agar plate and warm conditions provide the ideal place for bacteria to grow. The bacteria you obtained with the cotton ball grow steadily, becoming visible with the naked eye in a relatively short time. Different samples produce different results. What happened when you took a swab sample from your own body?

Want to grow your own bacteria using a hand-washing kit from Home Science Tools?

Is it safe to wash my hands in water?

When you want a glass of water, where do you usually get it from? Do you drink bottled water or get it from the tap? You probably don’t drink from a pond (although people in many countries do.) Why do we have these different ways of getting water? Is there anything really different about bottled water, tap water, and lake water? Let’s find out!

Materials:

three different water samples (see experiment below)
microscope with slides and coverslips
notebook with pencil for sketching

Experiment:

Obtain three water samples – tap water, bottled water, and water from outside. (The “outside” water could be a stream, lake, or just a puddle.)
Make slides using several drops of each water sample.
Observe the slides under the microscope.
Make drawings of what you see, comparing and contrasting each sample.

Is soap better than sanitizer?

In this activity, you will compare the ability of bar soap and hand sanitizer to remove bacteria from your hand. This is another example of using the scientific method to answer questions and solve problems.

Materials:

soap
hand sanitizer
petri dish
agar
cotton call or cotton swab

Experiment:

Wash one of your hands with bar soap and clean the other with a hand sanitizer.
Swab each hand with a cotton ball and rub each swab in a Petrie dish with agar.
Place in a warm place and allow to sit for several days.
Compare the bacteria growth in each plate. Which method of cleaning was more effective?

Learn how well you wash your hands by viewing the germs under a UV light with the Glo Germ kit from Home Science Tools (Do you already have the UV light from Unit 9? Just get the bottle of glow germ gel.)

Here are several additional bonus experiments you can do with the rest of the glo gel you have left over!

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Latest News

What’s Going On?

What’s Going On?

Experiment

Kidneys Process Fluids Data Table

Kidneys Filtration Data Table

C1000: Experiment

Here’s the breakdown of the entire process:

Going Further

C1000: Experiments

C3000: Experiment

C3000: Experiment

C3000: Experiment

C3000: Experiment

Going further: Elephant’s Toothpaste

C3000: Experiment

C3000: Experiments

C3000: Experiment

Click here for Homework Problem Set #14

C3000: Experiments

Click here to go to next lesson on Characteristics and capacity of buffers

Follow cleanup instructions carefully for safety. These are very toxic substances we are working with.

C3000: Experiments

Going Further

Testing Iodine solution

Addition with Iodine

Sodium Thiosulfate

Packing Peanut

Colorless Iodine

Iodine and Heat

Colorless Iodine Without Heat

Click here to download Equilibrium Constants and Reaction Mechanisms.

C3000: Experiment

Click here to download Homework Problem Set #9.

C3000: Experiment

How to Care for your TAC (Terra-Aqua Column) EcoSystem:

Fruit Fly Trap

Predator-Prey Column

What’s Going On?

Questions to Ask

Worm Column

Garden Worm Tower

Build your own worm farm and watch them turn food scraps into soil!

Earthworm Dissection

NEVER pick wild mushrooms! In addition to the uncertainty in the type of mushroom, there’s also possible harmful bacteria growing on the mushroom.

Grow Your Own Bacteria

What's happening?

Is it safe to wash my hands in water?

Is soap better than sanitizer?