Topics

Lasers, Jell-O and Trigonometry

Thursday March 20, 2014

If you’re scratching your head during math class, wondering what you’ll ever use this stuff for, here’s a cool experiment that shows you how scientists use math to figure out the optical density of objects, called the “index of refraction”.

How much light bends as it goes through one medium to another depends on the index of refraction (refractive index) of the substances. There are lots of examples of devices that use the index of refraction, including fiber optics. Fiber optic cables are made out of a transparent material that has a higher index of refraction than the material around it (like air), so the waves stay trapped inside the cable and travel along it, bouncing internally along its length. Eyeglasses use lenses that bend and distort the light to make images appear closer than they really are.
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Materials:

Paper
Laser
Pencil
Protractor
Ruler
Gelatin (1 box)
1/2 cup sugar
2 containers
Hot (boiling) water with adult help
Knife with adult help

Download Student Worksheet & Exercises

Experiment:

Mix two packets of gelatin with one cup of boiling water and stir well.
To one of the containers, add 1/2 cup sugar. Label this one as “sugar” and put the lid on and store it in the fridge.
Label the other as “plain” and also store it in the fridge. It takes about 2 hours to solidify. Wait, and then:
Cut out a 3”x3” piece of gelatin from the plain container.
On your sheet of paper, mark a long line across the horizontal, and then another line across the vertical (the “normal” line) as shown in the video.
Mark the angle of incidence of 40^o. This is the path your laser is going to travel on.
Lay down the gelatin so the bottom part is aligned with the horizontal line.
Shine your laser along the 40^o angle of incidence. Make sure it intersects the origin.
Measure the angle of refraction as the angle between the bent light in the gelatin and the normal line. (It’s 32^o in the video.)
Use Snell’s Law to determine the index of refraction of the gelatin: n₁ sin θ₁ = n₂ sin θ₂
Repeat steps 4-10 with the sugar gelatin. Did you expect the index of refraction to be greater or less than the plain version, and why?

Questions to Ask:

Does reflection or refraction occur when light bounces off an object?
Does reflection or refraction occur when light is bent?
What type of material is used in a lens?
What would happen if light goes from air to clear oil?

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Reflection Law using a Laser

Thursday March 20, 2014

The angle that the reflected light makes with a line perpendicular to to the mirror is always equal to the angle of the incident ray for a plane (2-dimensional) surface.

We’re going to play with how light reflects off surfaces. At what angle does the light get reflected? This experiment will show you how to measure it.

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Materials:

laser
mirror
protractor
pencil
paper

These downloads are provided by Laser Classroom. Check out their website for more free downloads and really cool lasers!

Click here for the chapter in optics for advanced students.

Did you notice a pattern? When the laser beam hits the mirror at a 30^o angle, it comes off the mirror at 60^o, which means that the angle on both sides of a line perpendicular to the mirror are equal. That’s the law of reflection on a plane surface.

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Refraction using Lasers and Water

Thursday March 20, 2014

This simple activity has surprising results! We’re going to bend light using plain water. Light bends when it travels from one medium to another, like going from air to a window, or from a window to water. Each time it travels to a new medium, it bends, or refracts. When light refracts, it changes speed and wavelength, which means it also changes direction.

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Materials:

Red and green laser
Paperclip
Index card
Tape
Rubber band
Water glass

Open the paperclip into an “L” shape, and tape it to an index card so the card stands up. This is your projection screen.
Use the rubber band to attach the laser pointers together. You’ll want them very close and parallel to each other. Place the rubber band close to the ON button so the laser will stay on when you put the rubber band over it.
Place the laser pointers on a stack of books and put switch them on with the rubber band.
Shine the lasers through the middle of an empty glass jar and onto the screen.
Put a mark where the red and green laser dots are on the screen.
With the lasers still on, slowly fill the container with water. What happened to the dots?
You can add a couple of drops of milk or a tiny sprinkling of cornstarch to the water to see the beams in the water.

Here’s a quick activity you can do if the idea of refraction is new to you… Take a perfectly healthy pencil and place it in a clear glass of water. Did you notice how your pencil is suddenly broken? What happened? Is it defective? Optical illusion? Can you move your head around the glass in all directions and find the spot where the pencil gets fixed? Where do you need to look to see it broken?

When light travels from water to air, it bends. The amount it bends is measured by scientists and called the index of refraction, and it depends on the optical density of the material. The more dense the water, the slower the light moves, and the greater the light gets bent. What do you think will happen if you use cooking oil instead of water?

So the idea is that light can change speeds, and depending on if the light is going from a lighter to an optically denser material (or vice versa), it will bend different amounts. Glass is optically denser than water, which is denser than air. Here’s a couple of values for you to think about:

Vacuum 1.0000
Air 1.0003
Ice 1.3100
Water 1.3333
Pyrex 1.4740
Cooking Oil 1.4740
Diamond 2.4170

This means if you place a Pyrex container inside a beaker of vegetable oil, it will disappear, because it’s got the same index of refraction! This also works for some mineral oils and Karo syrup. Note however that the optical densities of liquids vary with temperature and concentration, and manufacturers are not perfectly consistent when they whip up a batch of this stuff, so some adjustments are needed.

Questions to Ask

1. Is there a viewing angle that makes the pencil whole?

2. Can we see light waves?

3. Why did the green and red laser dots move?

4. What happens if you use an optically denser material, like oil?
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Laser Safety

Thursday March 20, 2014

Most people know not to shine lasers into sensitive places like eyeballs, but very few people can tell one laser from another. The truth is that not ALL lasers are dangerous, and there are different classifications of lasers. The most important information you need about laser safety is printed right on the laser itself.

Basic Laser Guidelines for Safety:
1. Never look directly at the beam source, or aperture
2. Never point the beam at another person
3. Always be mindful of where a “bouncing beam” will land due to reflection

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Download your student worksheet here! This download is provided by Laser Classroom. Check out their website for more free downloads and really cool lasers!

How do you enforce safety? After kids are familiar with laser classification (below), let them know that if you spot any dangerous activity around using a laser, the laser is yours (the adult) to keep forever. Period.

Are green lasers more dangerous than red lasers?

Laser Classification

Class 1 or Class I lasers do not emit hazardous levels of optical radiation. You’ll find theses types of lasers in the scanners of grocery stores at the check out counter. The beam paths and reflections are all enclosed.

Class 2 or Class II lasers are low-power visible lasers around 1 mW (milliwatt), and you’d really have to try hard to get injured by one of these types of lasers. Officially, it’s stated that this type of laser can have possible eye damage if you stare at the beam directly without blinking for at least 15 minutes.

Class 3 has two different levels of lasers, one being much more dangerous than the other.

Class 3a or IIIa lasers are 1 to 5 mW power and can’t injure you normally, but if you stare at the beam through something with lenses, like binoculars, then your eyes are toast.

Class 3b or IIIb lasers are lasers from 5mW to 500 mW, and these are the ones that cause eye injury with you look at them without any eye protection. These are NOT the ones you want kids playing with, as eye protection is always required when around these lasers.

Class 4 or IV are above 500 mW and these require not only eye protection to be around, but also skin protection. These lasers cause damage by the beam and the reflections of the beam, and are also a fire hazard.

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Tech Light Lab Experiments

Thursday March 20, 2014

This set of experiments will show you the properties of light, including optics, diffraction, transmission, reflection, wavelength, intensity, and so much more. You’ll discover how light travels in a straight line, how light can turn a corner, split into several beams, and why objects can appear dark even when light is shining right on them.

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Materials: You can order all these parts in one kit called the Tech Light Lab!

three flashlights
fingernail polish (red, blue, and green)
clear tape
small mirror
paperclip
old CD or diffraction grating
clear pieces to shine your light through
protractor
pencil
ruler
index cards (3)
paper
three objects: one red, one blue, and one green
aluminum foil
tack
water glass
binder clip (optional)

This is a longer video that has several experiments on it. I left them all together in one long video, as the experiments build on each other, and this set is best done all together. You should be able to complete all of the experiments in about 35-45 minutes. Here are the experiments in the video:

Diffraction Gratings
Does Light Travel in a Straight Line?
Exploring Shadows
Reflecting Light
Bouncing Light
Adding Light
Bending Light
Refraction

Download your student worksheet here!

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Guesstimations

Monday February 3, 2014

When it’s too hard to count ’em up and too much time to calculate, it’s time to guesstimate the answer. I use this technique all the time to “ball park” my answer so I know if I’ve made a mistake with my final answer.

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Download the student worksheet that goes with this lesson.

This lesson is useful when you don’t need an exact answer, or if the numbers are way too long to remember. It’s really pretty simple to do: you round up or down, and the closer to the ones digit you can handle, the more exact your answer will be.
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Division

Monday January 6, 2014

If you hate long division like I do, then this lesson will be very useful in showing you how to make the most out of your division tasks without losing sleep over it. It's easy, quick, and a whole lot of fun! If you haven’t already mastered your multiplication tables, make sure you have one handy to refer to as you go along.

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Download the student worksheet that goes with this lesson.

Many, many thanks go to Arthur Benjamin, a mathematics professor extraordinaire and professional magician who inspired much of this content we covered today.
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Quicker Multiplication

Monday December 23, 2013

If you don’t have the patience to do multiplication on paper for every single math problem that comes your way, then you’ll really enjoy this math lesson! You’ll be able to multiply one and two digit numbers in your head, which you’ll be able to use when checking your answers on a math test, or just whenever you need to multiply something quickly when paper’s not around.
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Download the student worksheet that goes with this lesson.

If you haven’t already mastered your multiplication tables, make sure you have one handy to refer to as you go along.
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Math from Left to Right

Monday December 9, 2013

In school, you are trained to solve math problems on paper, at a desk. The problem with that is, for most people, math problems don’t usually come with a desk or a pencil. They pop up in the checkout line when paying for groceries, figuring out your gas mileage at the pump, or when counting calories at a restaurant. Learning how to solve math problems in your head is an essential everyday life skill, especially if you don’t want to be ripped off in money transactions.

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Download the student worksheet that goes with this lesson.

Learning how to calculate in your head doesn’t have to be hard or scary, but it does require a little rewiring of the current math solving conditioning that you’ve already got in your brain. Specifically, we’re going to train your mind that when you solve math problems without paper, you must do it from left to right. It’s so much easier to think about math problems from left to right, so that’s how we’re going to do them.
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Multiplication Tables

Monday November 25, 2013

If you haven’t memorized your multiplication table yet, I am going to show you how to you need to memorize only three of the 400 numbers on a 20 times table in order to know your table.

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Download the student worksheet that goes with this lesson.

Math isn’t about solving problems on any one particular way, but rather it’s about puzzling the solution out multiple ways! The times table is essential to doing math in your head, but you don’t need to know every cell on the table by heart. With a couple of quick tips and tricks, you’ll be able to know your table up to 20 without a lot of memorization simply by being clever about the way you go about it.
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Magic of 11's

Monday October 28, 2013

This math lesson is so easy that one night, I wound up showing it to everyone in the pizza restaurant. Well, everyone who would listen, anyway. We were scribbling down the answers right on the pizza boxes with such excitement that I couldn’t help it – I started laughing right out loud about how excited everyone was about math - especially on a Saturday night.

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Download the student worksheet that goes with this lesson.

When you do this calculation in front of friends or family, it’s more impressive if you hand a calculator out first and let them know that you are ‘testing to see if the calculator is working right’. Ask for a two digit number and have them check the calculator’s answer against yours.
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Shopping List for Unit 20

Thursday September 5, 2013

Here is the list of materials for doing ALL the experiments in the entire Unit 20 section on atmosphere and geology.

How many of these items do you already have? We’ve tried to keep it simple for you by making the majority of the items things most people have within reach (both physically and budget-wise), so you can pick and choose the experiments that fit with what you’d like to do. Since the lessons for Earth Science require very different materials, we’ve keep them in two separate itemized lists for you.

Here’s how to use this shopping list: First, look over the list and circle the items you already have on hand. Browse the experiments and note which ones use the materials you already have. Those are the experiments you can start with. After working through the experiments, your child might want to expand and do more activities. Make a note of the materials and put them on your next shopping trip OR order them online using the links provided below.

We’ve tried to keep it simple for you by making the majority of the items things most people have within reach (both physically and budget-wise). Are you ready?

Shopping List for Unit 20: Earth Science Click here for Shopping List for Unit 20.

NOTE: Radio Shack part numbers have been replaced. Click here for full chart.

Lesson 1: Atmosphere

activated carbon (found in a fish store)
alcohol burner or votive candle
alum (found in the grocery or drug store)
balloons (5)
black paint or spray (flat, not glossy)
black piece of paper
bowl
business card or index card
Celsius/Fahrenheit thermometer
cheese cloth
chemistry stand (optional)
clay
cotton balls (2)
Diaper Genie refill, or large plastic bags.
disposable cups (4)
disposable pie tin (2)
drill bits and drill with adult help
duct tape, masking tape
electric fan
film canister or soup can
food dye (red and blue)
funnel
garbage bag (lightweight, plastic)
glass jars (3)
glasses (2, identical)
gloves
goggles
hair dryer (hand held)
hair, single
highlighter (silver, or some aluminum foil)
hole punch
ice cubes
ketchup packet
lighter (with adult help)
lime (calcium hydroxide, found in gardening store)
marker

measuring cups
measuring spoons (1/4 and 1/2)
medicine dropper or syringe dropper
newspaper
paintbrush
paper
paper clips
pencil with eraser on top
pepper
ping pong ball
pinwheel (can be purchased or made from construction paper)
popsicle sticks (2)
right-angle glass tube inserted into a single-hole stopper (optional)
rubber tubing (optional)
rubbing alcohol
ruler
salt
saltwater
sand (clean sand)
scissors
shoe box (small child’s size)
soda bottle (two liter)
soda cans (3, empty)
sodium acetate
stopwatch
stove or burner (with adult help)
straws (25)
string (about 4 feet long)
Sun print paper or other paper sensitive to light
tacks or pins
tape
test tube (or medicine dropper)
test tube clamp
water bottles
wire screen

Lesson 2: Geology

Mineral & Rock Samples (These are the ones we used in the videos, but if you have your own collection, use those!)

- “Flowering Rock” dolomite samples
- “Geology Field Trip” rock samples
- “Washington Student Rock Pack” 40 student samples
  (see list below for samples that are included)
- OPTIONAL: Fluorescent Minerals
- OPTIONAL: “Know Your Minerals” (also called “Learn Your Minerals”) set
  by Geoscience Industries
- OPTIONAL: “Know Your Rocks” (also called “Learn Your Rocks”) set
  by Geoscience Industries

Supplies:

acetic acid (plain distilled white vinegar)
ammonia (adult supervision required!)
baking soda powder
borax (sodium tetraborate)
calcium hydroxide (also known as “lime”)
calculator
copper sulfate crystals
dirt
disposable paper cups (6)
eggshell halves (4), cleaned
empty egg carton
Epsom salts
flour
food coloring
funnel
glass (plate)
glass jar
goggles
hammer
kitchen sponge (2)
laundry bluing
longwave UV light (included in the fluorescent minerals kit above)
magnet
magnifying lens (handheld)
measuring cup (milliliters (mL))
measuring tape
medicine dropper
mixing bowl

oil
paper clip
paper towels
paperclip
pennies (50)
penny
pie tins (6)
pipe cleaners (or string or skewer)
Plaster of Paris
plastic spoon
pliers (to bend paperclip)
Polyurethane A & B
popsicle sticks
rubber stopper
ruler
salt
sand
scale (measures in grams)
scissors
shell (something to make a fossil of)
sodium silicate
steel nail
stove, pan, and adult help
straw
string
sugar
test tube
toilet paper
unglazed porcelain tile
votive candle
water bottles (2)
wooden skewer

Introduction

Tuesday September 3, 2013

We’re about to dive into a comprehensive course that teaches the big ideas behind rocks, minerals, and the science of geology. Soon you’ll learn how to burn coal, fluoresce minerals, chemically react rocks, streak powders, scratch glass, and play with atomic bonds as they learn how to be a real field geologist.

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Everything is matter. Well, except for energy, but that’s everything else. Everything you can touch and feel is matter. It is made up of solid (kind of) atoms that combine and form in different ways to create light poles, swimming pools, poodles, Jell-O and even the smell coming from your pizza.

All matter is made of atoms. Shoes, air, watermelons, milk, wombats, you, everything is made of atoms. Hundreds and billions and zillions of atoms make up everything. When you fly your kite, it’s atoms moving against the kite that keep it in the air. When you float in a boat, it’s atoms under your boat holding it up.

My definition of an atom is: the smallest part of stable matter. There are things smaller than an atom, but they are unstable and can’t be around for long on their own. Atoms are very stable and can be around for long periods of time. Atoms rarely hang out on their own, though. They are outgoing and usually love to get together in groups. These groups of atoms are called molecules. A molecule can be made of anywhere from two atoms to millions of atoms. Together these atoms make absolutely everything, including the minerals, crystals, and rocks we’re about to study.

A periodic chart has a bunch of boxes. Each box represents one element. In each box is a ton of information about each element. All atoms are made from the same stuff; it’s just the amount of stuff that makes the atoms behave the way they do.

If you look at a periodic table you will notice that there will be about 112 to 118 different elements (this will vary depending on how recently the table was created). About 90 of those occur naturally in the universe. The other ones have been man-made and are very unstable. So imagine: Everything in existence, in the entire universe, is made of one or several of only about 90 different types of atoms. Everything, from pianos to pistachios are made from the same set of 90 different Legos!

Now, if you find that amazing, listen to this: Almost everything in the universe is mostly made of only twelve different kinds of atoms! But wait, there’s more.

All living things are mostly made of only five different kinds of atoms! Five! You and a hamster are made of the same stuff! All living and once-living things are made mostly of carbon, hydrogen, oxygen, nitrogen, and calcium. Ta daa! Those are the ingredients for life. Put ‘em in a bowl, stir and voila, you can make your own penguin.

Okay, obviously it’s not that easy. It takes a lot more than that to make life, but at least now you know the ingredients. An easy way to remember the main ingredients for living things is to remember the word CHONC. Each letter in CHONC is the first letter in the 5 elements carbon, hydrogen, oxygen, nitrogen and calcium.

One last interesting thing to think about here: Of all the atoms in the entire universe, 90% of them are hydrogen. Only 10% of the entire universe is made up of anything other than hydrogen.

Throughout this course, we’re going to be talking about the chemical composition (what elements rocks are made of), so you’ll really understand chemistry and geology both!

Minerals are pure chemical substances, made up entirely of one molecule through and through. Examples of minerals are everywhere. Rock salt is a mineral called halite. Fool’s gold is a mineral called pyrite. They are made of a single substance and nothing else. Rocks are composed of two or more minerals. We’re going to study rocks, minerals, crystals, and more in our unit on geology!

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Color Streak

Tuesday September 3, 2013

You will be able to identify minerals by their colors and streaks, and be able to tell a sample of real gold from the fake look-alike called pyrite.

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Materials

1 handheld magnifying lens
Unglazed porcelain tile
Rock samples (the ones in the video are: graphite, pyrite, talc, iron, and jasper)

Download worksheet and exercises

Every mineral has a set of unique characteristics that geologists use to test and identify them. Some of those tests include looking at the color of the surface, seeing if the mineral is attracted to a magnet, dripping weak acids on the rock to see if they chemically react, exposing them to different wavelengths of light to see how they respond, scratching the rocks with different kinds of materials to see which is harder, and many more. There are more than 2,000 different types of minerals and each is unique. Some are very hard like diamonds, others come in every color of the rainbow, like quartz and calcite, and others are very brittle like sulfur.

The color test is as simple as it sounds: Geologists look at the color and record it along with the identification number they’ve assigned to their mineral or rock. They also note if the color comes off in their hands (like hematite). This works well for minerals that are all one color, but it’s tricky for multi-colored minerals. For example, azurite is always blue no matter where you look. But quartz can be colorless, purple, rose, smoky, milky, and citrine (yellow).

Also, some minerals look different on the surface, but are really the same chemical composition. For example, calcite comes in many different colors, so surface color isn’t always the best way to tell which mineral is which. So geologists also use a “streak test”.

For a streak test, a mineral is used like a pencil and scratched across the surface of a ceramic tile (called a streak plate). The mineral makes a color that is unique for that mineral. For example, pink calcite and white calcite both leave the same color streak, as does hematite that comes in metallic silvery gray color and also deep red. This works because when the mineral, when scratched, is ground into a powder. All varieties of a given mineral have the same color streak, even if their surface colors vary. For example, hematite exists in two very different colors when dug up, but both varieties will leave a red streak. Pyrite, which looks a lot like real gold, leaves a black streak, while gold will leave a golden streak.

The tile is rough, hard, and white so it shows colors well. However, some minerals are harder than the mineral plate, like quartz and topaz, and you’ll just get a scratch on the plate, not a streak.

Number your rock samples by placing them on your data table.
Using your data table, record the color of each sample.
Now use your streak plate. Take a rock and draw a short line across your streak plate (unglazed porcelain tile).
Record the color of the streak in your data table. Are there any surprises?

Exercises

What does it mean if there’s no streak left?
Give an example of a kind of rock that leaves a streak a different color than its surface color.
What is a mineral that appears in two different colors, yet leaves the same color streak?

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Mohs’ Hardness

Tuesday September 3, 2013

By the end of this lab, you will be able to line up rocks according to how hard they are by using a specific scale. The scale goes from 1 to 10, with 10 being the hardest minerals.
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Materials

Steel nail
Penny
Small plate of glass (optional)
Rock samples (minerals in the video: talc, selenite, calcite, fluorite, apatite, feldspar, quartz)

Download worksheet and exercises

The sample’s hardness is determined by trying to scratch and be scratched by known materials, like pennies, steel, glass, and so forth. If the material leaves a mark on the mineral, then we know that the material is harder than the mineral is. We first start with a fingernail since it’s easy to use and very accessible. If it leaves a mark, that means that your fingernail is harder than the mineral and you know it’s pretty soft. Talc is one of the softest minerals, making it easy to scratch with your fingernail.

However, most minerals can’t be scratched with a fingernail, so we can try other objects, like copper pennies (which have a hardness of 2.5-3.5), steel nail (3.5-5.5), steel knife (5.5), and even quartz (7). The most difficult part of this experiment is keeping track of everything, so it’s a great opportunity to practice going slowly and recording your observations for each sample as you go along.

Number your samples on the data table and place each rock on the table. If you have the same samples listed above, you can scratch each rock with every other rock to find where they are on the Mohs’ Hardness Scale, where 1 is the softest and 10 is the hardest:
Mohs’ Scale of Hardness Talc
1. Selenite
2. Calcite
3. Fluorite
4. Apatite
5. Feldspar
6. Quartz
7. Topaz
8. Corundum
9. Diamond
If you don’t have one of each from the following scale (at least up to quartz), then you’ll need to do this experiment a different way – the way most geologists do it in the field. Here’s how:
Scratch one of the rocks with your fingernail. If you can leave a mark, then write “Y” in the second column of the data table. Now skip over to the last column and estimate the hardness to be less than 2.5.
If you can’t scratch it with your fingernail, try using the mineral to scratch a copper penny. If it doesn’t leave a mark on the penny, skip over to the last column and estimate the hardness to be between 2.5-3.5.
If it does leave a scratch on the penny, then try scratching the mineral with a steel nail. If the nail leaves a scratch, skip over to the last column and estimate the hardness between 3.5-5.5.
If you can’t scratch the sample with the nail, see if the mineral can make a scratch on the plate glass. Glass has a hardness of 6-7. If it doesn’t make a scratch on the glass, then it’s between 5.5-6.5. If it does, it’s higher than 6.5. For example quartz will make a scratch on the plate, and its hardness has been recorded at 7.

Exercises

If a mineral scratches a penny but doesn’t get scratched by a nail, can you approximate its hardness?
Give examples of the hardest and softest minerals on the Mohs’ Scale.
Is feldspar harder or softer than quartz?

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Cleavage & Fracture

Tuesday September 3, 2013

Today, you’ll learn what to look for in a broken mineral. There are different names for the types of breaks that a mineral can experience. You’ll need to ask a few important questions during your investigation, like, “What is the difference between mineral cleavage and fracture?”

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Materials

Mineral samples
Hand lens
Good lighting

Download worksheet and exercises

Cleavage and fractures are two properties that geologists test at the same time, both by observations. Using a hammer, geologists will break a mineral by studying how the mineral broke. They describe the way the surfaces look. Sometimes minerals break apart like they were stacked together in thin sheets. Other times they break off in large chunks, and the sides of each chunk are always at right angles. The way that they break into planes is called “cleavage.” Minerals can have cleavage in one direction, like mica, or two or three directions (like halite). The type of cleavage is also described using geometric terms. Halite has cubic cleavage because when it breaks, it looks like it’s made up of tiny cubes, while calcite has rhombic cleavage because it never breaks into right angles, but always in a rhombus, or diamond shape.

Fracture describes the surfaces that are broken but don’t break along plane lines. A mineral can have both cleavage and fracture, and some have either one or the other. Quartz has no cleavage, only fracture. Calcite has no fracture, only cleavage. Feldspar has both.

Geologist look for smooth surfaces, which can be (when viewed up close) cubes, triangles, or simple, flat plane surfaces. Always look for cleavage first, then fracture when making your data observations.

An easy way to look for cleavage is to hold the sample in sunlight and look for surfaces that reflect light and describe the surface in one of three ways for cleavage:

Perfect – the mineral breaks to reflect a clear, glass, or mirror-smooth surface.
Good – the mineral breaks to reveal a surface that reflects light, but may be dull in places.
Poor – the mineral breaks along clear planes and flat spaces are visible, but these are dull and could be ragged, and not very reflective.

Remember, a mineral can have more than one cleavage plane. For example, feldspar has two cleavages, one which is perfect and one which ranges from poor to good, depending on the sample. At first glance, you might not be able to tell feldspar from quartz, but if you look for cleavage, you’ll find feldspar has two planes of cleavage whereas quartz has none. Quartz will look like lots of broken surfaces that are not flat planes.

The way a mineral breaks depends on what the crystalline structure looks like. Here are some forms of cleavage:

Basal cleavage is cleavage on the horizontal plane, like mica. Basal cleavage samples can sometimes have their layers peeled away.
Cubic cleavage is found in mineral that have crystals that look like cubes., like with galena or halite.
Octahedral cleavage is found on crystals that have eight-sided crystals, like two pyramids with their bases stuck together. Look for flat, triangular wedges that peel off an octahedron, like in the mineral fluorite.
Prismatic cleavage is found in minerals that have four or more sides and are long in one direction, like aegirine, where the crystal cleaves on the vertical plane.
Rhombohedral cleavage is really my favorite, because it shows up in calcite so well due to its internal crystal structure, which is made up of hexagonal crystals. No matter where you look, there are no right angles to this cleavage – everything is at an angle.

Fracture can be described like this:

Conchoidal (like a shell, for example: obsidian)
Earthy (looks like freshly broken soil, like limonite)
Hackly or jagged (when a mineral is torn, like with naturally occurring silver or copper)
Splintery (looks like sharp, long fibrous points, like chrysolite)
Uneven (rough surface with random irregularities, like pyrite and magnetite)
Even or smooth (the fracture forms a smooth surface)

You will begin by labeling each of the mineral samples, starting with 1. Make sure to keep track of these samples throughout the entire lab.
Take the mineral samples and note which number it is on your observation data sheet.
Using your hand lens, look carefully for little sparkles of surfaces that reflect light. These are the cleavage surfaces.
In the space marked cleavage on your worksheet, label the cleavage as perfect, good, or poor. If there are no flat surfaces that are broken, write “none.” Some of your samples may have more than one cleavage. Make a note if this is the case.
Now look for broken surfaces that are not flat. Place a check below the best category of fracture that the mineral shows. If there are no surfaces like this, mark “none.” If you are uncertain about either category, leave the section blank. It is better to record no information than to mark something that can mess up your data.

Exercises

Which properties do geologists look for when they try to categorize a mineral? Circle all that apply.
1. Color
2. Shine
3. Smell
4. How it breaks
If you break a sample of quartz and find that it has no clean surfaces of separation, what kind of cleavage does it show?
True or false: A mineral can show more than one type of cleavage or fracture.
What is a fracture called that is similar to glass?

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Acid Test

Tuesday September 3, 2013

Your goal is to identify samples according to their reactivity with acid. Minerals that react are called chemical rocks, and minerals that don’t are called clastic rocks. Some chemical rocks contain carbonate minerals, like limestone, dolomite, and marble which react with the acid.
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Materials

Acetic acid (plain distilled white vinegar) in a dropper bottle or in a small cup with a medicine dropper
Pie tin
Paper towels
Steel nail
Optional: handheld magnifier
Rock samples (in the video: bituminous coal, limestone, conglomerate, coquina, shale, siltstone, sandstone, and dolomite)

Download worksheet and exercises

If your sample fizzed, you’ve got carbonate in your sample, and your sample might be calcite, marble, coquina, or limestone. If the powder fizzed, you’ve probably found dolomite, which is similar to calcite except it also has magnesium, which bonds more tightly than calcium, making the sample less reactive than limestone.

The reaction doesn’t always occur quickly. Sometimes you’ve got to be patient and wait. For example, magnesite has a weak reaction with acid, and if you grind it to a powder and then test, you have to wait half a minute for tiny bubbles to form. Magnifiers are helpful for these smaller, weaker reactions.

A lot of rocks contain small amounts of calcite or other carbonate minerals, so all of these make a fizz even though carbonate is only a small part of the rock. There might be small veins or crystals of carbonate minerals that you can’t even see, yet when you place a drop of acid on them, they bubble up. You can tell these types of rocks from the real thing because you won’t be able to do more than one acid test on them. The second time you try to add a drop of acid, there will be no reaction. The acid test is just one of many tests used, and shouldn’t be the only one that you use to determine your sample’s identification.

Chemically speaking, when you add the acid to the samples, you’re dissolving the calcium in the samples and releasing carbon dioxide gas into the air (these are the bubbles you see during the reaction).

For calcium carbonate and vinegar, the reaction looks like this:

2CH3COOH + CaCO3 → Ca(CH3COO)2 + H2O + CO2

The first term on the left CH3COOH is the acetic acid (vinegar), and the second term CaCO3 is the calcium carbonate. They both combine to give water H2O, carbon dioxide CO2, and calcium acetate Ca(CH3COO)2.

Carbonate minerals that react with acid (either vinegar or hydrochloric acid (HCl) as shown in the video) include aragonite, azurite, calcite, dolomite, magnesite, malachite, rhodochrosite, siderite, smithsonite, strontianite, and witherite. You can increase the reactivity with HCl by warming the HCl solution before using for the acid test.

You can do this experiment in other ways, too! Place a piece of chalk in a cup of vinegar and watch the tiny bubbles form on the chalk. This also works for egg shells, because they also contains calcium.

Do not let kids test their minerals with hydrochloric acid.

(For teachers demonstrating the HCl version of this test: CaCO3 + 2HCl → Ca++ + 2Cl–+ H2O + CO2)

Note: a few rocks, like coquina, oolite, and tufa can produce an extreme reaction with hydrochloric acid because they have a lot of calcite, and/or a lot of pore space that allows for high surface areas (exposing more of the calcium carbonate to the acid). The reaction will be quick, foamy, and vigorous, which is why we only use one drop of acid at a time.

Number and label your samples using the data table.
Use a dropper to take vinegar out of its bottle.
Drop a few drops onto your sample and watch for a reaction. You’re looking for bubbles, both in size and quantity. A few tiny bubbles don’t count. You’re looking for a reaction similar to the baking soda and vinegar reaction you are probably familiar with.
Optional: check with your hand lens while the reaction is taking place.
Record your observations in your data table.
Wipe your samples dry with a clean, damp cloth.
Test the hardness of your sample with the nail and record it in your data table. If the sample is softer than the nail, you’ll see a scratch and a powder left behind. Scratch it a couple of times to dig up more powder, then add a drop of the vinegar to the powder. Record your results. Did you see bubbles on the powder?

Do not let kids test their minerals with hydrochloric acid. (For teachers demonstrating the HCl version of this test: CaCO₃ + 2HCl → Ca⁺⁺ + 2Cl^—+ H₂O + CO₂) Note: a few rocks, like coquina, oolite, and tufa can produce an extreme reaction with hydrochloric acid because they have a lot of calcite, and/or a lot of pore space that allows for high surface areas (exposing more of the calcium carbonate to the acid). The reaction will be quick, foamy, and vigorous, which is why we only use one drop of acid at a time. Exercises

What state(s) of matter is/are present during the chemical reaction of the acid test?
Write the chemical equation that describes the reaction using your own words. For example, to make water, you’d write: oxygen + hydrogen = water. What would you write for the reaction on the rocks?

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Sedimentary, Metamorphic, and Igneous Rocks

Tuesday September 3, 2013

Clastic rocks come in very different shapes and sizes, but they all have a few characteristics in common. A clast is a grain of sand, gravel, pebble, etc that makes up a rock. Clastic rocks look like they are made up of fragments of other rocks.

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Materials

Small piece of plate glass
Magnifying lens
Vinegar
Paper towel
Shallow dish
Rock samples (in the video: bituminous coal, sandstone, siltstone, shale)

Metamorphic rocks are classified by as being foliated or non-foliated. Foliated rocks have layers, like bands around the rock. Non-foliated rocks don’t have any layers are are solid-looking throughout, although they might have crystals here and there. If the crystals are aligned to form a layer, then it’s a foliated rock.

Igneous rocks are classified as being extrusive or intrusive. An intrusive rock has a courser grain texture without a magnifier. Extrusive rocks need a magnifier to see the finer grains that make up the rock. Some extrusive rocks, like obsidian, need a microscope to see the fine grains.

Download worksheet and exercises

Clastic sedimentary rocks are fragments of other rocks. Geologists look at the tiny particle grains that make up the rock when they name the rock. For example, mudstone is named for its tiny particles of mud and clay, and sandstone is made up of larger grains of sand. The conglomerate rocks look like they are made up of pebbles. Siltstone under a strong magnifier show microscopic grains.

Number and label your samples with your data table.
Take your hand magnifier and look closely at each sample and record the color information on the data table.
Use a dropper to take vinegar out of its bottle.
Drop a few drops onto your sample and watch for a reaction. If you see a reaction, note this in the data table and classify the rock as a chemical rock, not a clastic rock.
Wipe your samples dry with a clean, damp cloth.
Test the hardness of your sample with the nail and record it in your data table using Mohs’ Hardness Scale.

Exercises

Give three types of clastic sedimentary rocks.
How can you tell a clastic from a non-clastic rock?
Does hardness determine a clastic rock? If so, what hardness do you expect a clastic rock to have?

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Burning Coal

Tuesday September 3, 2013

Bituminous coal (also called black coal) is a soft, black organic sedimentary rock that contains 85% carbon. It’s a lower grade than anthracite coal, which contains 93% carbon. Bituminous coal can either be dull or shiny, whereas anthracite is hard and shiny. Lignite, a lower grade than bituminous, is a crumbly, black type of coal that only contains 72% carbon.

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Materials

Votive candle
Paperclip
Hammer (if your piece of coal is large)
Pliers (to bend paperclip)
Lighter with adult help
Cup of water
Rock samples (in the video: bituminous coal, anthracite coal)

Download worksheet and exercises

Coal comes in two main forms: bituminous and anthracite. Bituminous coal is the stuff used to generate energy, whether electricity, heated water, or as a product in other substances. It’s more abundant than anthracite, which is the purer version of coal. Anthracite burns hotter and cleaner, but it’s more scarce. Coal also exists in two other forms as peat, which used to serve as fuel for heating homes as well as lignite, which is more pure than peat but not quite as pure as bituminous.

Coal is one of the two kinds of rocks that are not made from minerals (amber is the other).

Today’s lab lets you burn coal to identify the byproducts of combustion. When coal is burned, it releases volatile compounds that are hazardous to your health, including methane, hydrogen, carbon monoxide, carbon dioxide, nitrogen, and volatile hydrocarbons, but the chemical reaction leaves behind a purer form of carbon than found in the coal itself. So make sure to do this experiment outside!

Move your experiment outside. Do not do this indoors! Fumes generated must be properly ventilated.
Open up and bend the paperclip into a shape that will allow you to hold the coal without it falling off the end. Use pliers to bend the paperclip.
Set a small piece (about the size of a pea) of bituminous coal at the end of the paperclip.
Put on your goggles. NO EXCEPTIONS!
Have an adult light your candle.
Place the coal piece at the top of the flame for the most intense heat.
Look for brown to black smoke to come from the coal. Record your observations in your data table.
When you’re done, place the entire piece of coal in your cup of water.

Optional: If you’ve got a test tube and stand, you can do the following experiment:

Put on your goggles, and pick up the test tube with the test tube holder.
Place a small piece of bituminous coal in the test tube (about the size of a pea).
Place the tube at an angle in a proper holder.
Turn on the heat source, and wave it near the bottom of the test tube for a few minutes, until you notice any slight changes.
As your coal sample heats up, look for bubbles or gas, which is coal gas, one of the first of three things produced by coal. The coal gas was captured and used as fuel in household lamps and streetlights before electricity was available.
As you continue to heat the sample, look for brown stuff along the sides of the tube called coal tar, which is used in dyes, aspirin, textiles, pesticides, and more.
As your sample continues to burn, notice if there are any gray-black solids in the bottom. This will look a lot like ash, but it’s called coke and it’s used to purify metals in a chemical process.

Exercises

What are the three products that coal generates?
Name four types of coal.
What are two things we use coal for?
What type of coal is the most pure?
What is the dominant element in coal?
What are three alternatives to generating energy, instead of using coal?

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Tenacity

Tuesday September 3, 2013

Tenacity is a measure of how resistive a mineral is to breaking, bending, or being crushed. When you exceed that limit, fracture is how the mineral breaks once the tenacity (or tenacious) limit has been exceeded.

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Materials

Hammer (if your piece of coal is large)
Rock samples (in the video: copper, mica, selenite, sulfur)

Download worksheet and exercises

Tenacity is a measure of how a mineral behaves when under stress, like being crushed, bent, torn, or hammered. Minerals will react differently to each type of stress. Minerals can have more than one type of tenacity, since it’s possible for a mineral to have different (or several at the same time) reactions to the stress. Here’s a way to classify their response to stress:

Brittle: The sample crumbles or turns into a powder. Most minerals are brittle, like quartz.
Sectile: These minerals can be separated with a knife, like wax, like gypsum.
Malleable: When you hammer the mineral and it flattens instead of breaks, it’s malleable like silver and copper.
Ductile: A mineral that can be stretched into a wire is called ductile. All true metals are ductile, like copper and gold.
Flexible-Inelastic: When you bend a mineral and release it, it stays in the new shape. It was flexible enough to bend, but it didn’t snap back into its original shape when released, like copper.
Flexible-Elastic: When you bend a mineral and release it, it springs back into its original shape. Minerals that are flexible-elastic are fibrous, like chrysotile serpentine.

Label and number each of your samples with your data table.
Use a hammer and try to break the copper sample. Make sure you do this on a hard surface (like the concrete) so you don’t damage your floor or table!
To test for brittleness, like for sulfur, do a scratch test to see if it leaves a fine powder. Use your streak plate if you think your specimen has a hardness of less than 7.
For sectile tenacity, like with mica, carefully insert a knife into the mineral to see if it goes through. If the knife can penetrate through the sample (be careful with this!), then it’s sectile.
To check for flexibility, like mica and selenite, use only slight pressure so you don’t break your sample. Notice if the sample springs back or retains its new shape when released.
Complete the data table with your observations.

Exercises

What are four different types of tenacity?
How is elastic different from inelastic tenacity?
How many types of tenacity can a mineral have?

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Density

Tuesday September 3, 2013

Density can be found by weighing an object and dividing by the volume of the object, and for geologists, is the same thing as specific gravity. Water has a density of 1, which means that 1 gram of water takes up 1 cubic centimeter of space. Specific gravity is a number you get when you divide the density of an object by the density of water, which happens to be 1 gram/cm3.

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Materials

Measuring cup that has graduation marks for milliliters (mL)
Scale that measures in grams
Rock samples (in the video: quartz, meteorite, pumice)

Download worksheet and exercises

The specific gravity (also called the “s.g.” or “SG”) of a mineral or rock is how we compare the weight of the sample with the weight of an equal volume of water. Low specific gravity substances, like pumice (0.9), are not very dense. High specific gravity substances, like for gold (19.3), are very dense. If the specific gravity is less than 1, it will float on water.

Density is a way to measure two different minerals that might be exactly the same size, but their weights are different. Minerals with a metallic luster tend to be heavier. You’ll find variations for SG within the same minerals due to impurities of the mineral. Along those lines, this test can’t be done for material that is embedded within a rock, only for a single sample.

Here are a few examples for you to compare your samples with:

Amber 1.1
Quartz 1.5
Obsidian 2.5
Amethyst 2.6
Diamond 3.5
Hematite 5.05
Pyrite 5.1
Gold 19.3

Label and number each of your samples and record this on your data table.
Weigh each sample and record the information on your table.
Fill your cup with water and note the level.
Completely submerge your sample and read the new water height.
Subtract #4 from #3 answers to get the amount of water your sample displaces. Record this in your data table.
Find the volume of water displaced for every sample.
Divide the mass of the object by the volume to find the density: ρ = m / V with the units of grams / mL
Note: 1 mL = 1 cm³

Exercises

In your data table, which number was the same for every trial run?
What is the equation for finding density?
How did you find the volume of the rock?

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Luster

Tuesday September 3, 2013

Luster is the way a mineral reflects light, and it depends on the surface reflectivity.

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Materials

Sunlight
Rock samples (in the video: pyrite, fluorite, and serpentine)

Download worksheet and exercises

Every mineral has a particular luster, but some have different luster on different samples. Since it’s gauged by eye and not a scientific instrument, there’s quite a lot to be left to the observer when describing it. Luster is not usually used to identify minerals, since it’s so subjective.

That said, it is useful when describing a sample’s surface, so hold up yours to the light and use the descriptions below to find the one that best describes what you see.

Metallic or splendent luster are found in highly reflective minerals, like gold.
Submetallic luster is found in minerals that have a similar luster to metal, but it’s a bit duller and less reflective. These minerals are opaque and reflect light well. You’ll find submetallic luster in the thin splinter sections of minerals, such as sphalerite, cinnabar, and cuprite.
Vitreous or glassy luster describes 70% of all minerals, and they have the luster of glass. Quartz, calcite, topaz, beryl, tourmaline, and fluorite are examples of glassy luster.
Adamantine lusters (brilliant, like a cut diamond) are for transparent materials that show a very bright shine because they have a high refractive index.
Resinous lusters are usually yellow, orange, or brown minerals that have high refractive indices (like the way sunlight goes through honey).
Silky lusters have very fine fibers aligned in parallel, so it looks like a cloth of silk. Minerals like asbestos, ulexite, and a variety of gypsum called satin spar all have silky luster. If a sample has fibrous luster, it is coarser than a silky luster.
Pearly luster minerals look like the way light reflects off pearls, like the inside an oyster shell. These types of minerals have perfect cleavage, like muscovite and stilbite. Mica also has a pearly luster. Some pearly luster minerals also have an iridescent hue.
Greasy or oily luster looks like fat, and is found in minerals that have a lot of microscopic inclusions, like opal and cordierite. Most greasy luster minerals also feel oily.
Pitchy luster looks a lot like tar, and is found in radioactive minerals.
Waxy luster resembles wax, the way jade and chalcedony look on their surface.
Dull or earthy luster minerals have very little or no luster at all, because they have a surface that scatters the light in all directions, like with Kaolinite. Some geologists say that earthy luster means less luster than dull, but it’s really a close call between the two.

When light strikes a surface, it can be reflected off the surface, like a mirror, or it can pass through, like a window, or both. Metallic luster has most of the light bouncing off the surface, whereas calcite has most passing through the mineral. When light travels through a mineral, it refracts, or changes speed, as it crosses the new material boundary. This is what makes the luster appear different for different materials.

Refraction is how light bends when it travels from one substance to another. When light moves through a prism, it bends, and the amount that it bends is seen as color that comes out the other side. Each color represents a different amount of bending that it went through as it traveled through the prism.

Label and number each of your samples and record this on your data table.
Hold your mineral in the sunlight.
Use the list to find the word that best describes what you see. Look particularly on your sample for a surface that is clean and not tarnished, discolored, or coated. Look at cleaved surfaces and on uneven parts.

Metallic
Submetallic (duller than metallic)
Vitreous or glassy
Adamantine (like a cut diamond)
Resinous (like honey)
Silky (like a silk cloth)

Pearly
Greasy or oily
Pitchy (like tar)
Waxy (like a candle)
Dull or earthy

Record your observations in the data table.

Exercises

What is refraction?
Feldspar has perfect cleavage on two surfaces but fractured on a third. What kind of luster would you say it has?
What type of luster is found on mica?

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Fluorescence

Tuesday September 3, 2013

Fluorescent minerals emit light when exposed to ultraviolet (UV) light, usually in a completely different color than when exposed to white light. UV is invisible to the human eye, and is the wavelength of light that is responsible for sunburns.

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Materials:

Longwave UV light
Sunlight
Rock samples (The four samples at the end of the video are: top left is opalite, top right is calcite, bottom left is norbergite, bottom right is calcite & willemite.)

Download worksheet and exercises

Stars, including our sun, produce all kinds of wavelengths of light, even UV. The UV minerals in this lab contain a substance that reacts with light. It takes the UV light from the sun and then re-emits it in a different wavelength that’s visible to us.

When a particle of UV light hits an atom in the mineral, it collides with an electron which makes the electron jump to a higher, more energetic state that is a bit further from the center of the atom than the electron is used to. That’s how energy gets absorbed by an atom. The amount of energy an electron has determines how far from the atom it has to be.

The electron prefers being in its lower state, so it relaxes and jumps back down, and when it does, it transfers a blip of energy away. This blip of energy is the light we see emitted from the UV mineral. This process continues as long as we see a color coming from the mineral under the UV light.

There are two different types of UV wavelengths: longwave and shortwave. Some minerals fluoresce the same color when exposed to both wavelengths, while others only fluoresce with one type, and still others fluoresce a different color depending on which it’s exposed to. Minerals fluoresce more notably with shortwave UV lamps, but these are more dangerous than longwave since they operate at a wavelength that also kills living tissue.

Shortwave UV lamps and lights should only be operated by an experienced adult. Never use a shortwave light when children are around.

Most minerals do not fluoresce, but in the ones that do, there are either small impurities that fluoresce (called “activators”) or the pure substance itself fluoresces (although this is rare). For a mineral to fluoresce, the impurities present must be in just the right amount. For example, red fluorescent calcite from Franklin, NJ, USA is activated by manganese that’s present, but only if there’s about 3% of it in the mineral. If there’s more than 5% or less than 1% manganese, the sample won’t fluoresce at all. It’s the amount and type of the impurities that determines the color and intensity of the fluorescence.

Fluorescence is not a reliable way to identify a mineral, since some samples will fluoresce with different colors even though they are all the same mineral. Fluorescence is used to determine where the mineral came from, since the colors that the minerals fluoresce usually match the original location of the mineral.

Phosphorescence is when a sample glows even after you turn off the UV light source. This is the type of glow you’ll find in “glow in the dark” toys, where the light slowly fades after you turn off the light. Atoms continue to emit light even after the electrons return to their normal energy states. While it looks like seconds to minutes that the glow lasts, some samples have been found to phosphoresce for years using highly sensitive photographic methods. Only a few minerals phosphoresce, such as calcite from Terlingua, Texas.

Label and number each of your samples and record this on your data table.
Hold your mineral in the sunlight and record the color in the data table.
Go inside and turn off the lights. Hold your sample under a longwave UV light and record the colors that you see.
Complete the data table.

Aragonite
Hackmanite
Calcite
Fluorite
Opalite
Calcite & willemite
Tremolite
Resinous coal
Wernerite

Aragonite
Termolite
Wiollemite
Opalite
Chalcedony
Calcite & willemite
Talc
Resinous coal
Norbergite
Calcite

Exercises

What wavelength is shortwave UV? Longwave UV?
How is fluorescence different from phosphorescence?
Name two minerals that fluoresce in both shortwave and longwave UV light.

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Magnetism

Tuesday September 3, 2013

A magnetic field is the area around a magnet or an electrical current that attracts or repels objects that are placed in the field. The closer the object is to the magnet, the more powerfully it’s going to experience the magnetic effect. Nearly all minerals that are magnetic have iron as a component.

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Materials:

Magnet
Rock samples (samples in the video that stuck to the magnet are lodestone [which is the magnetic form of magnetite] and meteorites)

Download worksheet and exercises

Minerals can become attracted to a magnetic field if they are heated to a certain temperature. These minerals become ferromagnetic after heating them up. Some minerals also act as magnets when they are heated, but this effect is only temporary for as long as the mineral stays at that temperature.

Magnetism is a very useful way of identifying a mineral, because it’s so precise. When testing for magnetism, you’ll get better results if you use the strongest magnet you can find. You’ll find minerals that respond to magnets (without heating them up first) are metallic-looking samples.

Most student-grade geology books refer to minerals that are attracted to magnetic fields as “magnetic,” which leads to confusion because there’s a difference between being “magnetic” (acting as a magnetic field) and being “attracted to magnetic fields.” When you fill out your observations in the data table, keep this in mind when you write down what you see by using the words “magnetic” or “attracted to a magnetic field.”

Label and number each of your samples and record this on your data table.
Hold your mineral close to the magnet and observe how strongly it is attracted to the magnet. How far away do you have to be to start influencing the sample?
Complete the data table.
There are several magnetic properties that geologists use to specify the type of magnetism within a mineral:
- Ferromagnetism is the kind of magnetism you’ll see in magnetite and pyrrhotite, as these have strong attraction to magnetic fields.
- Paramagnetism is a weak attraction to magnetic fields, such as with the minerals hematite and franklinite.
- Diamagnetism occurs in only one mineral, bismuth, which means it’s repelled from magnetic fields.
- Magnetism is found in only one mineral called lodestone, which is the magnetic version of magnetite. It’s really rare, since it’s only found in a couple locations in the entire world. Lodestone is weakly magnetic, but if you drop small paperclips, staples, and iron filings onto a piece, they’ll stick.

Exercises

Is lodestone the same as magnetite?
Which mineral is repelled from any magnetic field?
Which element is usually present in minerals that have magnetic properties?

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Making Limestone

Tuesday September 3, 2013

Out of all the kinds of sedimentary rocks, limestone makes up 10% by volume. People have used limestone in architecture like the Great Pyramids, castles in Europe, and in early 20th century buildings like banks and train stations. Today we use it as white filler in toothpaste, to build roads, make tiles, in cosmetics, and added to breads and cereal as a cheap source of calcium.

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Materials:

Goggles
Distilled white vinegar (you only need a drop, so use a medicine dropper)
Funnel
Straw
2 water bottles
2 paper napkins
Calcium hydroxide (also known as “lime”) This chemical is irritating to skin and eyes, so use your goggles and gloves when handling since it’s a dust. This chemical is toxic and should only be handled by an adult. Find safety information under MSDS Calcium Hydroxide

DO NOT ALLOW CHILDREN TO DO THIS EXPERIMENT. Limewater is TOXIC. This experiment is for demonstration purposes only by an adult.

STUDENTS: You can watch the video and complete the data table and exercises if you’re not able to have an adult do this for you

Download worksheet and exercises

Limestone is a sedimentary rock that is mostly calcium carbonate, and some amazing fossils have been found in limestone. In our experiment today, we are doing a simple chemistry experiment that produces calcium carbonate as the product. The calcium carbonate is created from a chemical reaction of the carbon dioxide from your breath mixed with calcium hydroxide. Only 4-5% of your breath is converted into carbon dioxide, so it takes awhile to get enough carbon dioxide through the solution to form the calcite crystals and see the color change happen.

Put on your goggles and gloves.
Fill one of your water bottles partway with water.
Add a spoonful of calcium hydroxide.
Cap the calcium hydroxide and store safely away.
Place the cap on the water bottle and shake up the solution. Set aside and do not disturb for several minutes.
Fold your napkin into a shape that will fit into your funnel. This is a liner for your funnel that will catch the solids as they are poured into the funnel.
Put a little water into your funnel to dampen the paper napkin liner.
Place the second (empty) water bottle under the funnel.
Pour the limewater solution through the funnel. Don’t pour the sludge at the bottom into the funnel.
Insert a straw into the water bottle with the strained limewater.
Write down the color of the solution. Is it cloudy? Clear?
Blow gently into the straw for several minutes until you see a color change. DO NOT INHALE. Limewater is very toxic!
What color did the color change to? Record your observations in the data table.
Test the calcite by pouring the solution through a new paper funnel.
Place a drop of acetic acid (distilled white vinegar) on the calcite crystals and watch for a slight reaction.

Exercises

What element is present in both calcium carbonate and your breath when you exhale?
Why aren’t kids allowed to do this experiment? What’s the danger?
Where can you find safety information for chemicals?

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Making Sandstone

Tuesday September 3, 2013

Sandstone is a common sedimentary rock that’s composed of quartz crystals cemented together by silica, calcium carbonate, clay or iron oxide. Fossils are often found in sandstone.

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Materials

2 paper cups
Water
Popsicle stick
Sand
Plaster of Paris
Shell (something to make a fossil impression of)
Scissors

Download worksheet and exercises

One way geologists classify sandstone is by the amount of quartz, feldspar, and lithic grains it contains. Quartz sandstone is composed of more than 90% quartz grains, while feldspathic sandstones has less than 90% quartz, but more feldspar than lithic grains. Lithic sandstones have both less than 90% quartz and more lithic grains. In addition, if a geologist calls a sample “clean sandstone,” then it means that there are tiny holes in the sample, like pores. They’ll add the word “arenite” to the name, so you might hear “quartz arenite” which means a sandstone that has more than 90% of its grains as quartz and is also porous.

Pour enough sand to cover the bottom of one of the cups.
In the second cup, make a 1:1 mixture of Plaster of Paris and water. (You can add food dye to make the plaster more visible when layered, but this is optional.)
Stir to combine with the popsicle stick.
Pour a layer right on top of the sand.
Add more sand to the first cup.
Now add more plaster.
Continue adding in layers until you have at least six layers (three of each), but you can do more if you have enough room and materials.
Do not mix the layers.
Cover the last layer with sand.
If you’re making a fossil impression, first rub vegetable oil over it (so the sand doesn’t stick) and press firmly into place without twisting or pushing too hard. Allow it to dry for 24 hours.
When it’s dry, carefully remove the fossil on top and see the impression you’ve made!
Tear away the cup to see the different layers of your homemade sandstone.

Exercises

What elements is calcium carbonate made out of? (Carbon and oxygen.)
How does this experiment look like sandstone? (The tiny grains of sand are glued together by the Plaster of Paris.)
What do you know about a feldspathic arenite sample? (The sample has less than 90% quartz, but more feldspar than lithic grains, and it’s porous.)

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Popcorn Rock

Tuesday September 3, 2013

Popcorn rocks are different than regular dolomite samples because they have a lot more magnesium inside. This was first discovered by a geology professor in the 1980s who was dissolving the limestone around fossils he was studying in his rock samples. When he placed samples of this type in the acid to dissolve, it didn’t dissolve but instead grew new crystals!

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Materials:

“Flowering Rock” dolomite samples
Distilled white vinegar (acetic acid)
Disposable cup or glass jar
Penny
Nail
Streak plate
Water in a graduated container
Scale that measures in grams
Longwave UV light source
Sunlight

Download worksheet and exercises

Dolomite is made of calcium magnesium carbonate (CaMg(CO3)2 and is both a mineral and a rock. Dolomite comes in all kinds of colors, including white, gray, pink, peach, yellow and orange … even colorless. Dolomite gives a white streak, which is hard to see on a white streak plate, and the hardness ranges from 3.4 to 4 on the Moh’s hardness scale. Specific gravity for dolomite is 2.8 to 3, with a vitreous (glassy), pearly luster and rhombohedra cleavage on two planes and conchoidal fracture on the third. It’s brittle (think tenacity), and is usually found around limestone. Dolomite is a chemical rock, since it reacts to acid. Dolomite fluoresces bluish-white when placed under a longwave UV light, and pink when exposed to a shortwave UV light.

You’re first going to classify dolomite and test it for certain properties, and then you’ll grow crystals all over it. If you don’t have a UV light, skip it and perform the rest of the tests.
Complete the first data table for the sample before following the instructions on the video. You are looking for the color, streak, hardness, density, luster, cleavage, fracture, tenacity, acid reaction, and fluorescence.
Don’t wash your dolomite sample. You want the dust layer on top so the crystals start growing more quickly.
Place the sample in your glass jar.
Pour the vinegar into the cup (not directly on your sample) until it’s nearly submerged.
Move your experiment to a warm location.
Observe your rock formation over the next week and record your observations in the second data table. You can opt to take pictures and paste them into the data table.
When all the vinegar has evaporated, remove the sample and put on display (after recording your last observation).

Exercises

What would happen if you warmed the vinegar first, and placed it on a heating pad during your experiment?
What is it in the dolomite samples that make the aragonite crystals grow?
What else can you try instead of vinegar?

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Foam Pumice

Tuesday September 3, 2013

Today we’re making polyurethane foam, which looks a lot like pumice in that it’s lightweight, porous, and cream colored. Polyurethane is a polymer that is used to make a variety of products, including seat cushions, insulation panels, seals and gaskets, roller coaster wheels, escalator rollers, carpet underlay, and wheels for skateboards.
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Materials:

Two disposable plastic cups (must be disposable)
Craft stick
Tart pan
Polyurethane A
Polyurethane B
Sample of pumice for observation

Download worksheet and exercises

Pumice is used to make concrete, cinder blocks, and cement. The Roman Pantheon and aqueducts used pumice as one of their construction materials. Today, you’ll find pumice in polishes because it’s an abrasive. It’s also on the tip of your pencil as an eraser and on your toothbrush inside your toothpaste. If you’ve ever owned a pair of stone-washed jeans, you now know what stone was used to get that look on the pants. Beauty salons use pumice stones for pedicures and chinchillas use powdered pumice to bathe in, since they don’t like to get wet.

Put on your goggles and gloves – NO EXCEPTIONS.
Now, move your entire experiment outside, because this experiment generates fumes that you don’t want to breathe in.
Put the two cups in the pan.
Pour a couple tablespoons of polyurethane A into the first cup.
Pour a couple tablespoons of polyurethane B into the second cup. You need a 1:1 ratio unless otherwise indicated on your package of the product.
Pour one cup into the other, and stir, stir, stir! Your solution will look like honey, so keep stirring. When it starts to get cloudy and foam up, stop stirring.
Touch the bottom of the cup every 10 seconds with a gloved finger (do not touch the liquid itself). What do you notice?
After about a minute, the foam should be rising up and out of the cup. This is polyurethane foam, but don’t touch it yet.
The foam will continue to build up until it spills out over the cup’s lip. DO NOT TOUCH the foam. When the foam is reacting, you should notice heat being released by holding a hand over (without touching!) the top of the rising solution. This reaction is exothermic because it releases heat energy.
When it’s cool, you can touch it with a gloved finger (it’s irritating to the skin, so always use gloves). Record your observations and clean up thoroughly following the instructions for disposal on your package.

Exercises

Name three characteristics of pumice.
How is pumice different from scoria?
What can you use pumice for?

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Test Tube Cannon

Tuesday September 3, 2013

You’ll learn about the key ingredient in an explosive eruption like the one we’re simulating in lab today.

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Materials:

test tube
rubber stopper
toilet paper
goggles
distilled white vinegar
baking soda powder
measuring tape
scale that weighs in grams
ruler

Download worksheet and exercises

Active volcanoes create domes inside the eruption chamber which act like giant plugs, stopping up the magma and building up pressure until … BOOM! The dome explodes and out comes all the material from inside, just like the plug in the test tube.

Baking soda (sodium bicarbonate) and vinegar (acetic acid) chemically react and combine to form carbon dioxide bubbles and a solid form of sodium acetate, which looks like little white flakes at the bottom of the solution.

For baking soda and vinegar, the chemical equation for the reaction looks like this:

NaHCO3 + HC2H3O2 → NaC2H3O2 + H2O + CO2

The chemical reaction actually occurs in two steps. The first reaction looks like this as the vinegar reacts with the baking soda to form sodium acetate and carbonic acid:

NaHCO3 + HC2H3O2 → NaC2H3O2 + H2CO3

But the carbonic acid isn’t a stable molecule, so it breaks down to make the carbon dioxide gas like this:

H2CO3 → H2O + CO2

Since the bubbles are heavier than air, the carbon dioxide builds up and overflows, and stays in the test tube until you dump it out.

Put on your safety goggles. NO EXCEPTIONS!
Tear off a single sheet of toilet paper.
Pour a small pile of baking soda right in the middle of the toilet paper.
Fold the toilet paper in half, and then wrap the sides around until you make a mini-burrito or mini-plug. You want it to fit snugly into your test tube (but don’t put it in there yet!)
Carefully pour vinegar into your test tube. You want about an inch (2-3 cm) of vinegar.
Gently push the toilet paper burrito plug into the test tube, but don’t let it touch the vinegar yet.
Push in your rubber stopper, making sure it’s nice and snug.
Point the stopper away from you or anyone else … like straight up.
Place a thumb on the stopper and shake the tube several times. Remove your thumb before the stopper pops!
After you’ve tried this a few times, it’s time to start taking real measurements. Here’s what you do:
Place the sheet of toilet paper on the scale and zero it (hit “tare”).
Add baking soda and record the mass of the baking soda (in grams) on your data table.
Fill your test tube with vinegar. Rest the bottom of the test tube on the table, and using a ruler, measure many centimeters of vinegar you added and record this number on your data table.
Roll up the toilet paper into the burrito plug and insert it into the test tube.
Add the stopper and shake!
Measure the distance that your stopper traveled in your data sheet and repeat the experiment until you’ve found the perfect ratio of baking soda and vinegar to make the stopper fly the farthest.

Exercises

Does the stopper go further when you add more or less vinegar?
Look at your answer for #1 above. Why is that?
Which gases are produced by this reaction?

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Making Fossils

Tuesday September 3, 2013

Today you get to make your own glop of earth that holds an embedded fossil. If you close the dough over the top of the fossil, you can hammer it apart after it’s had two days to dry.

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Materials:

½ cup dirt
½ cup flour
½ water
½ cup salt
shallow pan
oil
shell or other object to make a fossil impression of

Download worksheet and exercises

There are lots of collecting sites listed in geology field guides and books. Even if sites are popular, new fossils are exposed each spring after the winter’s weather. Another great resource is local fossil clubs, geologic societies, and local museums, especially those that participate in field trips. It’s a lot of fun to go collecting with a group, and many colleges and universities provide unique hands-on opportunities to students interested in earth science classes. Always make sure you’re allowed to collect before you go out with your tools … many local areas require permits.

Mix the dry ingredients together (dirt, flour, and salt) with your hands (or with a spoon).
Add the water and mix together well. Discard any pebbles or gravel from the dirt. You want a gloppy, clay-like mixture that holds together. Add more dry ingredients if needed.
Press the dough ball into the pan, making it ½- to 1-inch thick with ragged edges (fossils aren’t perfect).
Let dry overnight, or at least for a few hours if you’re in a hurry.
Coat the shell or object with oil and press it gently into the dough.
Let it dry thoroughly until it’s hardened. Remove your object and admire!

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Geology Field Trip

Tuesday September 3, 2013

Field trip time! Today you get to sift through sand and excavate your rock samples right on your own desk. This inexpensive set of rock samples contain pieces of not only fossils and gems, but true minerals and rocks also, so take your time and follow the video instructions carefully.

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Materials:

“Geology Field Trip” rock samples: dinosaur bone, horn coral, gastropod, brachiopod, trilobite, oyster, shark’s tooth, petrified wood, crinoid stem, pyrite, magnetite, gypsum, hematite, sulfur, pumice, selenite, limonite, quartz, mica, fluorite, calcite, feldspar, coal, red sandstone, conglomerate, obsidian, scoria, mica schist, quartzite, shale, gneiss, turquenite, rock crystal, agate, and amethyst.
Penny
Nail
Streak plate
Glass plate
Water in a graduated container
Sunlight
Pencil and paper
Handheld magnifier

Download worksheet and exercises

NEW! I’ve improved the worksheet, so you can download the latest edition here.

You’re first going to classify your pile of rocks right along with the instructional step–by-step video. So fire up the video and get your materials out as you complete the data table.
Use the table on the next page to place your rocks once you’ve identified them. Enjoy your second real geologist rock hunt

dinosaur bone
horn coral
gastropod
brachiopod
trilobite
oyster
shark’s tooth
petrified wood
crinoid stem
pyrite
magnetite
gypsum

hematite
sulfur
pumice
selenite
limonite
quartz
mica
fluorite
calcite
feldspar
coal
red sandstone

conglomerate
obsidian
scoria
mica schist
quartzite
shale
gneiss
turquenite
rock crystal
agate
amethyst

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Measure the Track Spacing of a DVD and CD

Sunday September 1, 2013

We’re going to use a laser pointer and a protractor to measure the microscopic spacing of the data tracks on a DVD and a CD. The really cool part is that you’re going to use an interference pattern to measure the spacing of the tracks, something that you can’t normally see with your eyes.

Interference is what happens when waves smack into each other. When the waves collide, if the two highest or two lowest points of the waves are lined up, then they add together to form a larger amplitude which is seen as a bright spot of light. However, if a peak and a trough line up, then they cancel each other out and there is a dark area in the pattern (see the dark spaces in the line?).

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On the CD or DVD, when white light shines on the surface, it makes a shimmering rainbow of colors. It does this because of diffraction, which is a more complicated form of interference.

We’re going to measure the data track spacing using a diffraction pattern and a little math. Here’s how to do it:

Materials:

Laser pointer (red works fine in a dark room)
CD
DVD
Protractor
Index card
Scissors
Tape
Cardboard box
Stack of books
Marker
Pencil
Clothespin
Brass fastener
Hot glue gun
Piece of grid paper

The equation to determine the distance is:

d_m = m λ / (sin θ_m – sin θ_i)

where λ is the wavelength of the laser, m = the order of the refraction ray, and d is the track spacing.

Watch the video to see how to do the calculations!

Questions:

Does a CD or DVD hold more data? How can you tell?
Is the track spacing larger, the same, or smaller for a DVD as a CD?
What is a diffraction grating?
How is diffraction different or the same as interference?
Why do you get more than one reflection when you shine the laser on the back surface of a CD? [/am4show]

Magnetic Tornadoes

Sunday September 1, 2013

This lab is a physical model of what happens on Mercury when two magnetic fields collide and form magnetic tornadoes.

You’ll get to investigate what an invisible magnetic tornado looks like when it sweeps across Mercury.

Materials

Two clear plastic bottles (2 liter soda bottles work well)
Steel washer with a 3/8 inch hole
Ruler and stopwatch
Glitter or confetti (optional)
Duct tape (optional)

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Download Student Worksheet & Exercises

Determine the different water conditions, such as: changing the temperature, changing the volume (height of water), adding another molecule such as oil, isopropyl alcohol, vinegar, and dish soap, adding solid pieces such as glitter, salt, sugar, or small grains. The different mixtures will give different vortex rotation speeds and different drain times. This is equivalent to changing the atmosphere on Earth and seeing how it affects weather (not magnetic) tornadoes. Write the conditions you wish to test in the data table before you start.
Fill one of the soda bottles with water using the data table. Set the bottle upright on the table.
Set the washer on top of the bottle opening. Make sure there’s no cap on the bottle.
Invert the empty bottle over the water‐filled bottle and line up the openings so they can be easily taped together. You want to tape them before they get wet with the washer between them.
Place the two bottles on a table and watch the water drip from the top to the lower bottle as air bubbles move from bottom to top.
Invert so the water is in the top bottle and circle it a couple of times to start a whirlpool in the bottle. You should see a vortex form inside as the top drains into the lower bottle. The hole in the vortex lets the airfrom the lower bottle flow easily into the upper bottle, so the upper drains easily.
When you’ve finished, empty your bottle and add a different solution and repeat the experiment.

What's Going On?

Mercury looks peaceful at first glance. However, when you measure the surface with scientific instruments, you’ll see how the Sun blasts away any hope Mercury has of a thin atmosphere with its radiation and solar wind. Not only that, Mercury is ravaged by invisible magnetic tornadoes that start from the planet’s interior magnetic field. If you’ve ever experienced a tornado, you know how terrifying they can be. Now imagine they are the diameter of your entire planet.

These tornadoes are different from the Earth’s, which form when two weather systems smack into each other, creating instability in the atmosphere. The magnetic tornadoes on Mercury form when two magnetic fields collide. These monstrous cyclones form without warning and disappear within minutes.

Magnetic fields, like the Earth’s, are invisible shields that constantly protect us from the Sun. Our Earth is constantly being bombarded with high energy particles that are deflected off the magnetosphere of our planet. Mercury’s magnetic field is weak and it’s constantly being blasted by solar wind, which also carries a magnetic field. When these two fields collide, the magnetic fields spiral and twist to form a magnetic tornado. (Solar wind is a stream of high energy particles from the Sun’s outer atmosphere.)

Exercises

Define an atmosphere.
What is a magnetic field?
Where do magnetic fields come from in planets?
Which planets do not have a magnetic field?

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Sundial

Sunday September 1, 2013

Using the position of the Sun, you can tell what time it us by making one of these sundials. The Sun will cast a shadow onto a surface marked with the hours, and the time-telling gnomon edge will align with the proper time.

In general, sundials are susceptible to different kinds of errors. If the sundial isn’t pointed north, it’s not going to work. If the sundial’s gnomon isn’t perpendicular, it’s going to give errors when you read the time. Latitude and longitude corrections may also need to be made. Some designs need to be aligned with the latitude they reside at (in effect, they need to be tipped toward the Sun at an angle). To correct for longitude, simply shift the sundial to read exactly noon when indicated on your clock. This is especially important for sundials that lie between longitudinal standardized time zones. If daylight savings time is in effect, then the sundial timeline must be shifted to accommodate for this. Most shifts are one hour.

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Download Student Worksheet & Exercises for ALL Sundials

Simple Sundial

Index card
Scissors
Tape

This sundial takes only a couple minutes to make, and reads easily for beginner students.
Cut the template.
Cut your index card into two triangles by cutting from one corner to the opposite diagonal corner. Stack the two triangles and tape together. This is called your gnomon.
Tape the triangle to your 12-hour line, putting tape on both sides of the gnomon as you stick it to the paper.
Put the sundial in a sunny place where it won’t be disturbed (like inside of a sunny window or on a table outdoors).
Point the sundial so that the gnomon is pointing north. This is most easily done if you orient your sundial at exactly noon in your location. Line up the sundial with the Sun so that the shadow the gnomon makes lines up exactly with the 12.
Tape the sundial down so it won’t move or get blown away.
The gnomon must be exactly perpendicular to the hour markers. Use a ruler or a book edge to help you line this up.

Intermediate Sundial

2 yardsticks or metersticks
Protractor
Chalk
Clock

Find a sunny spot that has concrete and grassy area right next to each other. You’re going to poke the yardstick into the grass and draw on the concrete with chalk, so be sure that the concrete goes in an approximately east-west direction.
First thing in the morning, stick one of the yardsticks into the dirt, right at the edge of the concrete.
At the top of the hour (like at 8 a.m. or 9 a.m.), go out to your yardstick to mark a position.
Lay the second yardstick down along the shadow that the upright yardstick makes on the ground. Use chalk to draw the shadow, and use the yardstick to make your line straight.
Label this line with the hour.
Set your timer and run back out at the top of the next hour.
Repeat steps 3-6 until you finish marking your sundial.
When you’ve completed your sundial, fill out the table.

Advanced Sundial

Old CD (this can also be the transparent CD at the top of DVD/CD spindles)
Empty CD Case
Skewer
Sticky tape
Cardboard or small piece of clay
Protractor
Scissors
Tape
Hot glue

This sundial will work for all longitudes, but has a limited range of latitudes. If you live in the far north or far south, you’ll need to get creative about how to mount the CD so that the gnomon is pointed at the correct angle. For example, at the equator, the CD will lie flat (which is easy!), but near the north and south poles, the CD will be upside down.

Cut out the timeline.
Put a line of double-sided sticky tape along the back of the timeline. Extend the tape about ¼” (on the bottom edge) so it’s hanging off a paper a little.
Flip the timeline over and roll the CD along this bottom edge, sticking the timeline to the edge of the CD. The timeline should be facing inward toward the center of the CD, perpendicular to the CD surface.
Now it’s time to plug up the center hole. You can cut out circles from a CD and attach with tape, or use a small piece of clay.
Push the skewer through the exact middle of the CD.
Open up the CD case.
Position the noon marker at the bottom and stick it using a piece of double-sided sticky tape or hot glue.
The other side of the CD is glued to the CD case at the same angle as your latitude. For example, if I live at 43^o north, I would use my protractor on the ground along the base of the CD case and lift the CD until the gnomon reads at 43^o. Put a dab of hot glue to attach the CD to the lid of the case.
Go outside and point the gnomon north (you may want to use a compass for this if it’s not noon.)
The dial will have a shadow that falls on the timeline. You can read the time right off the timeline.
For advanced students: Timeline correction: Do you remember how the Sun was fast or slow in the Stargazer’s Wall Chart from the lesson entitled: What’s in the Sky? That wavy line is called the Equation of Time, and you’ll need it to correct your sundial if you want to be completely accurate. This is a great demonstration for a Science Fair project, especially when you add a model of the Sun and Earth to help you explain what’s going on.

What’s Going On?

Sundials have been used for centuries to keep track of the Sun. There are different types of sundials. Some use a line of light to indicate what time it is, while others use a shadow.

Here are a couple of different models that, although they look a lot different from each other, actually all work to give the same results! Your sundial will work all days of the year when the Sun is out.

You’ll notice that north is the direction that your shadow’s length is the shortest. However, if you don’t know where east and west are, all you can do is know where north is. The equinox is a special time of year because the Sun rises in the exact east and sets in the exact west, making these two points exactly perpendicular with the north for your location (which they usually aren’t). At sunset, you can view your shadow (quickly before it disappears) and draw it with chalk on the ground, making a line that runs east-west. 90^o CCW from the line is north.

In general, sundials are susceptible to different kinds of errors. If the sundial isn’t pointed north, it’s not going to work. If the sundial’s gnomon isn’t perpendicular, it’s going to give errors when you read the time. Latitude and longitude corrections may also need to be made. Some designs need to be aligned with the latitude they reside at (in effect, they need to be tipped toward the Sun at an angle). To correct for longitude, simply shift the sundial to read exactly noon when indicated on your clock. This is especially important for sundials that lie between longitudinal standardized time zones. The Equation of Time from the advanced lesson entitled: What’s in the Sky? can be used to correct for the Sun running slow or fast. Remember, this effect is due to both the Earth’s orbit not being a perfect circle and the fact that the tilt axis is not perpendicular to the orbit path. If daylight savings time is in effect, then the sundial timeline must be shifted to accommodate for this. Most shifts are one hour.

Exercises

What kinds of corrections need to be made for your sundial?
When wouldn’t your sundial work?
How can you improve your sundial to be more accurate?

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Atmospheres

Sunday September 1, 2013

Scientists do experiments here on Earth to better understand the physics of distant worlds. We’re going
to simulate the different atmospheres and take data based on the model we use.

Each planet has its own unique atmospheric conditions. Mars and Mercury have very thin atmospheres, while Earth has a decent atmosphere (as least, we like to think so). Venus’s atmosphere is so thick and dense (92 times that of the Earth’s) that it heats up the planet so it’s the hottest rock around. Jupiter and Saturn are so gaseous that it’s hard to tell where the atmosphere ends and the planet starts, so scientists define the layers based on the density and temperature changes of the gases. Uranus and Neptune are called ice giants because of the amounts of ice in their atmospheres.

Materials

4 thermometers
3 jars or water bottles
Plastic wrap or clear plastic baggie
Wax paper
Stopwatch

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Place one thermometer in direct sunlight. This is like the atmosphere of Mercury and Mars.
Place a second thermometer in a jar and cap it. Place this in sunlight. This is the Earth’s, Jupiter’s and Saturn’s atmosphere.
Line the second jar with wax or tissue paper. Place the third thermometer in the jar and cap it. Place it next to the other two in sunlight. This is the atmosphere on Venus.
Insert the fourth thermometer into a plastic baggie, insert it into the bottle and cap it. Make sure the baggie is loose. This is Neptune and Uranus.
Record your data observations in the table, taking data every couple of minutes.

What’s Going On?

Venus is hot enough to melt cannonballs and crush any spaceship that tries to land on the surface. Carbon dioxide is a “greenhouse gas,” meaning that some wavelengths of light can pass through it, but specifically not infrared light, which is also known as heat. Light from the Sun either bounces off the upper cloud layers and back into space, or penetrates the clouds and strikes the surface of Venus, warming up the land. The ground radiates the heat back out, but the carbon dioxide atmosphere is so dense and thick that it traps and keeps the heat down on the surface of the planet. Think of rolling up your windows in your car on a hot day.

The heat is so intense on Venus that the carbon normally locked into rocks sublimated (turned straight from solid to gas) and added to the carbon in the atmosphere, to make even more carbon dioxide.

Mercury doesn’t have much of an atmosphere, which is just like a bare thermometer. There’s nothing to hold onto the heat that strikes the surface. Mars is in a similar situation.

Earth’s atmosphere is simulated by placing the thermometer in a bottle. The Earth has a cloud layer that keeps some of the heat on the planet, but most of it does get radiated back into space. When the clouds are in at night, the planet stays warmer than when it’s clear (and cold).

Venus’s heavy, dense carbon dioxide atmosphere is simulated by using the waxed paper. Venus is the hottest planet in our solar system because of the runaway greenhouse effect that traps most of the heat that makes it through the atmosphere, bouncing it back down to the surface. The average temperature of Venus is over 900^oF.

Jupiter and Saturn’s atmospheres are thinner layers of hydrogen and helium than deeper in the core.

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.

Exercises

Which atmosphere reached the highest temperature?
Each of the jars received the same amount of energy from the Sun. Why is this not quite like the real solar system?

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Fire & Optics

Sunday September 1, 2013

Today you get to concentrate light, specifically the heat, from the Sun into a very small area. Normally, the sunlight would have filled up the entire area of the lens, but you’re shrinking this down to the size of the dot.

Magnifying lenses, telescopes, and microscopes use this idea to make objects appear different sizes by bending the light. When light passes through a different medium (from air to glass, water, a lens…) it changes speed and usually the angle at which it’s traveling. A prism splits incoming light into a rainbow because the light bends as it moves through the prism. A pair of eyeglasses will bend the light to magnify the image.

Materials

Sunlight
Glass jar
Nail that fits in the jar
12” thread
Hair from your head
12” string
12” fishing line
12” yarn
Paperclip
Magnifying glass
Fire extinguisher
Adult help

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You’re going to concentrate the power of the Sun on a flammable surface.
Please do this on a fireproof surface! This experiment will damage tables, counters, carpets, and floors. Do this experiment on a fireproof surface, like concrete or blacktop.
Hold the magnifier above the leaf and bring it down toward the leaf until you see a bright spot form on its surface. Adjust it until you see the light as bright and as concentrated as possible. First, you’ll notice smoke, then a tiny flame as the leaf burns.
You are concentrating the light, specifically the heat, from the Sun into a very small area. Normally, the sunlight would have filled up the entire area of the lens, but you’re shrinking this down to the size of the dot that’s burning the leaf.
Thermoelectric power plants use this principle to power entire cities by using this principle of concentrating the heat from the Sun.
Never look through anything that has lenses in it at the Sun, including binoculars or telescopes, otherwise what’s happening to the leaf right now is going to happen to your eyeball.
Now for the next part of the lab, do not use water bottles – you want something that doesn’t melt, like a glass jar from the pickles or the mayo.
Remove the lid and punch a hole in the center. Use a drill with a ¼” drill bit or smaller, or a hammer and nail.
Screw the lid on the jar.
Tie one end of the thread to the paperclip.
Poke the other end of the thread inside the hole on the lid.
Unscrew the lid and tie a nail to the other end of the thread. You want the nail to be hanging above the bottom of the jar by an inch or two, so adjust the height as needed.
Bring your jar outside.
Question: Without breaking the glass or removing the lid, how can you get the nail to drop to the bottom of the jar?

What’s Going On?

Exercises

What happened to the leaf? Why?
How did you get the nail to drop?
Which material ignited the quickest?

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What’s Up in the Sky?

Sunday September 1, 2013

Today you get to learn how to read an astronomical chart to find out when the Sun sets, when twilight ends, which planets are visible, when the next full moon occurs, and much more. This is an excellent way to impress your friends.

The patterns of stars and planets stay the same, although they appear to move across the sky nightly, and different stars and planets can be seen in different seasons.

Materials:

Printout of Stargazer’s Almanac
Pencil
Tape and scissors (optional)
Ruler

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If your chart comes on two pages, you’ll need to cut the borders off at the top and bottom and tape them together so they fit perfectly.
Use your ruler as a straight edge to help locate items as you read the chart.
Print out copies of the almanac by clicking the image of the Skygazer’s Almanac. You can print it full-size on two pages, or size it to fit onto a single page. Since there’s a ton of information on it, it’s best read over two pages. This is an expired calendar to practice with.
First, note the “hourglass” shape of the chart. Do you see how it’s skinnier in the middle and wider near the ends? Since it’s an astronomical chart that shows what’s up in the sky at night, the nights are shorter during the summer months, so the number of hours the stars are visible is a lot less than during the winter. You’ll find the hours of the night printed across the top and bottom of the chart (find it now) and the months and days of the year printed on the right and left side.
Can you find the summer solstice on June 20? Use your finger and start on the left side between June 17 and June 24. The 20^th is between those two dates somewhere. Here’s how you tell exactly…
Look at the entire chart – do you see the little dots that make up little squares all over the chart, like a grid? Each dot in the vertical direction represents one day. There are eight dots on the vertical side of the box.
Let’s say you want to find out what time Neptune rises on June 17. Go back to June 17, which has its own little set of dots. Follow the dots with your finger until you hit the line that says Neptune Rises. Stop and trace it up vertically to the top scale to read just after 11 p.m.
Look again at the dot boxes. Each horizontal dot is 5 minutes apart, and every six dots there is a vertical line representing the half-hour. The line crosses between the second and third dot, so if you lived in a place where you can clearly see the eastern horizon and looked out at 11:07, you’d see Neptune just rising. Since Uranus and Neptune are so far away, though, you’d need a telescope to see them. So let’s try something you can find with your naked eye.
Look at Oct 21. What time does Saturn set? (5:30p.m.).
What other two planets set right afterward? (Mercury at 6:03 p.m. and Mars sets at 7:12 p.m.).
When does Jupiter rise? (7:32 p.m.).
What is Neptune doing that night of Oct. 21? (Neptune transits, or is directly overhead, at 8:07 p.m. and sets at 1:30 a.m.)
What other interesting things happen on Oct. 21? (Betelgeuse, one of the bright stars in the constellation Orion, rises at 9:23 p.m. Sirius, the dog star, rises at 11:06 p.m. The Pleiades, also known as the Seven Sisters, are overhead at 1:42 a.m.)
Let’s find out when the Moon rises on Oct. 21. You’ll find a half circle representing the Moon centered on 11:05 p.m. Which phase is the Moon at? First or third quarter? (First. You can tell if you look at the next couple of days to see if the Moon waxes or wanes. Large circles indicate one of the four main phases of the Moon.)
When does the Sun rise and set for Oct. 21? First, find the nearest vertical set of dots and read the time (5:30 p.m.). Now subtract out the 5-minute dots until you get to the edge. You should read three dots plus a little extra, which we estimate to be 17 minutes. Sunset is at 5:13 p.m. on Oct 21.
Note the fuzzy, lighter areas on both sides of the hourglass. That represents the twilight time when it’s not quite dark, but it’s not daylight either. There’s a thin dashed line that runs up and down the vertical, following the curve of the hourglass offset by about an hour and 35 minutes. That’s the official time that twilight ends and the night begins.
Can you find a meteor shower? Look for a starburst symbol and find the date right in the center. Those are the peak times to view the shower, and it’s usually in the wee morning hours. The very best meteor showers are when there’s also a new Moon nearby.
Notice how Mercury and Venus stay close by the edges of the twilight. You’ll find a half-circle symbol representing the day that they are furthest from the Sun as viewed from the Earth, which is the best date to view it. For Venus, the * indicates the day that it’s the brightest.
What do you think the open circle means at sunset on May 20? (New Moon)
Students that spot the “Sun slow” or “Sun fast” marks on the chart always ask about it. It’s actually rather complicated to explain, but here’s the best way to think about it. Imagine that the vertical timeline running down the center means noon, not midnight. Do you see a second line weaving back and forth across the noon line throughout the year? That’s the line that shows the when the Sun crosses the meridian. On Feb 5, the Sun crosses that meridian at 12:14, so it’s “running slow,” because it “should have” crossed the meridian at noon. This small variation is due to the axis tilt of the Earth. Note that it never gets much more than 15 minutes fast or slow. The wavy line that represents this effect is called the Equation of Time. We’ll be using that later when we make our own sundials and have to correct for the Sun not being where it’s supposed to be.
Look at Mars and Saturn both setting around the same time on Aug. 14. When two event lines cross, you’ll find nearby an open circle with a line coming from the top right side, accompanied by a set of arrows pointing toward each other. This means conjunction, and is a time when you can see two objects at once. Usually the symbol isn’t right at the intersection, because one of the objects is rising or setting and isn’t clearly visible. On Aug. 14, you’ll want to view them a little before they set, so the symbol is moved to a time where you can see them both more clearly.
Important to note: If your area uses daylight savings time, you’ll need to add one hour to the times shown on the chart.
Time corrections for advanced students: This chart was made for folks living on the 40^o north latitude and 90^o west longitude lines (which is Peoria, Ill.).
1. If you live near the standardized longitudes for Eastern Time (75^o), Central (90^o), Mountain (105^o) or Pacific (120^o), then you don’t have to correct the chart times you read. However, if you live a little west or east of these standardized locations, you need a correction, which looks like this:
  1. For every degree west, add four minutes to the time you read off the chart.
  2. For every degree east, subtract four minutes from the time.
  3. For example, if you lived in Washington, D.C. (which is 77^o longitude), note that this is 2^o west of the Eastern Time, so you’d add 8 minutes to the time you read off the chart. Memorize your particular adjustment and always use it.
2. If your latitude isn’t 40^o north, then you need to adjust the rise and set times like this:
  1. If you live north of 40^o, then the object you are viewing will be in the sky for longer than the chart shows, as it will rise earlier and set later.
  2. If you live south of 40^o, then the object you are viewing will be in the sky for less time than the chart shows, as it will rise later and set earlier.
  3. The easiest way to calculate this is to note what time an object should rise, and then watch to see when it actually appears against a level horizon. This is your correction for your location.
What’s Going On?

This is one of the finest charts I’ve ever used as an astronomer, as it has so much information all in one place. You’ll find the rise and set times for all eight planets, peak times for annual meteor showers, moon phases, sunrise and set times, and it gives an overall picture of what the evening looks like over the entire year. Kids can clearly see the planetary movement patterns and quickly find what they need each night. I keep one of these posted right by the door for everyone to view all year long.

Exercises

Is Mercury visible during the entire year?
In general, when and where should you look for Venus?
When is the best time to view a meteor shower?
Which date has the most planets visible in the sky?

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Kepler’s Swinging System

Sunday September 1, 2013

Johannes Kepler, a German astronomer famous for his laws of planetary motion. Check out our Johannes Kepler facts page for more information.

Kepler’s Laws of planetary orbits explain why the planets move at the speeds they do. You’ll be making a scale model of the solar system and tracking orbital speeds.

Kepler’s 1st Law states that planetary orbits about the Sun are not circles, but rather ellipses. The Sun lies at one of the foci of the ellipse. Kepler’s 2nd Law states that a line connecting the Sun and an orbiting planet will sweep out equal areas in for a given amount of time. Translation: the further away a planet is from the Sun, the slower it goes.
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What are the planets in our solar system starting closest to the Sun? On a sheet of paper, write down a planet and label it with the name. Do this for each of the eight planets.

Mercury is 0.39 AU (in a rocket it would take 2.7 months to go straight to Mercury from the Sun)
Venus is 0.72 AU
Earth is 1 AU (in a rocket it would take 7 months to go straight to Earth from the Sun)
Mars is 1.5 AU
Jupiter is 5.2 AU
Saturn is 9.6 AU
Uranus is 19.2 AU
Neptune is 30.1 AU (in a rocket it would take 18 years to go straight to Neptune from the Sun)

Of course, we don’t travel to planets in straight lines – we use curved paths to make use of the gravitational pull of nearby objects to slingshot us forward and save on fuel.

Now draw the location of the asteroid belt.
Draw the position of the Kuiper Belt” and ask a student to draw and label it (beyond Neptune).
Where are the five dwarf planets? They are in the Kuiper belt and the asteroid belt:
- Ceres (in the Asteroid belt, closer to Jupiter than Mars)
- Pluto (is 39.44 AU from the Sun)
- Haumea (43.3 AU)
- Makemake (45.8 AU)
- Eris. (67.7 AU)

Now for the fun part! You’ll need a group of friends to work together for this lab, so you have at least one student for each planet, one for the Sun, and two for the asteroid belts, and five for the dwarf planets. You can assign additional students to be moons of Earth (Moon), Mars (Phobos and Deimos), Jupiter (assign only 4 for the largest ones: Ganymede, Callisto, Io, and Europa), Saturn (again, assign only 4: Titan, Rhea, Iapetus, and Dione), Uranus (Oberon, Titania), and Neptune (Triton). If you still have extra students, assign one to Charon (Pluto’s binary companion) and one each to Hydra and Nix, which orbit Pluto and Charon. While you ask the students to walk around in a later step, the moons can circle while they orbit.

First, walk outside to a very large area.
Hand the Sun student the measuring tape.
Ask Kuiper Belt student(s) to take the end of the measuring tape and begin walking slowly away from the Sun.
With each student assigned to the distance shown, grab the measuring tape and walk along with it. Please be careful – measuring tapes can have sharp edges! You can use gloves when you grab the tape if you’ve got a sharp steel measuring tape to protect your hands. Ask the Sun to call out the distances periodically so the students know when it’s time to come up.
What do you notice about the distances between the planets? The nearest star is 114.5 miles away!
Ask the students to let go of the measuring tape, except for Neptune and the Sun. Everyone else gathers around you (a safe distance away, as Neptune is going to orbit the Sun).
Using a stopwatch, notice how much time it takes Neptune to walk around the Sun while holding the measuring tape taut. How long did it take for one revolution?
Now ask Mercury to take their position on the tape at the appropriate distance. Time their revolution as they walk around the Sun. How long did it take?
How does this relate to the data you just recorded for Neptune and Mercury? You should notice that the speeds the kids were walking at were probably nearly the same, but the time was much shorter for Mercury. If you could swing them around (instead of having them walk), can you imagine how this would make Mercury orbit at a faster speed than Neptune?
If you have it, you can illustrate how Kepler’s 2nd law works and relate it back to this experiment. Tie a ball to the end of a string and whirling it around in a circle. After a few revolutions, let the string wind itself up around your finger. As the string length shortens, the ball speeds up. As the planet moves inward, the planet’s orbital speed increases. The planet’s speed decreases the further from the Sun it is located.
Ask one of the bigger students to take their position with the measuring tape, reminding them to keep the tape taut no matter what happens. When they start to walk around the Sun, have the Sun move with them a bit (a couple of feet is good). Let the students know that the planet also yanks on the Sun just as hard as the Sun yanks on the planet. Since the planet is much smaller than the Sun, you won’t see as much motion with the Sun.
Optional demonstration to illustrate this idea: take a heavy bag (I like to use oranges) and spin it around as you whirl around in a circle. Do you notice the student leans back a bit to balance themselves as they swing around and around? This is the same principle, just on a smaller scale. The two objects (the bag and the student) are orbiting around a common point, called the center of mass. In our real solar system, the Sun has 99.85% of the mass, so the center of mass lies inside the Sun (although not at the exact center).
Look at the length of your measuring tape. Find the data table you need to use in the tables. Circle the one you’re going to use or cross out the ones you’re not.
Using a stopwatch, time Venus as they walk around the Sun while holding the measuring tape taut. How long did it take for one revolution? (Make sure the Sun doesn’t move much during this process like they did for the demonstration. We’re assuming the Sun is at the center.)
Continue this for all the planets.

What’s Going On?

Johannes Kepler, a German mathematician and astronomer in the 1600s, was one of the key players of his time in astronomy. Among his best discoveries was the development of three laws of planetary orbits. He worked for Tycho Brahe, who had logged huge volumes of astronomical data, which was later passed onto to Kepler. Kepler took this information to design and develop his ideas about the movements of the planets around the Sun.

Kepler’s 1st Law states that planetary orbits about the Sun are not circles, but rather ellipses. The Sun lies at one of the foci of the ellipse. Well, almost. Newton’s Laws of Motion state that the Sun can’t be stationary, because the Sun is pulling on the planet just as hard as the planet is pulling on the Sun. They are yanking on each other. The planet will move more due to this pulling because it is less massive. The real trick to understanding this law is that both objects orbit around a common point that is the center of mass for both objects. If you’ve ever swung a heavy bag of oranges around in a circle, you know that you have to lean back a bit to balance yourself as you swing around and around. It’s the same principle, just on a smaller scale.

In our solar system the Sun has 99.85% of the mass, so the center of mass between the Sun and any other object actually lies inside the Sun (although not at the center).

Kepler’s 2nd Law states that a line connecting the Sun and an orbiting planet will sweep out equal areas in for a given amount of time. The planet’s speed decreases the further from the Sun it is located (actually, the speed varies inversely with the square‐root of the distance, but you needn’t worry about that). You can demonstrate this to the students by tying a ball to the end of a string and whirl it around in a circle. After a few revolutions, let the string wind itself up around your finger. As the string length shortens, the ball speeds up. As the planet moves inward, the planet’s orbital speed increases.

Embedded in the second law are two very important laws: conservation of angular moment and conservation of energy. Although those laws might sound scary, they are not difficult to understand. Angular momentum is distance multiplied by mass multiplied by speed. The angular momentum for one case must be the same for the second case (otherwise it wouldn’t be conserved). As the planet moves in closer to the Sun, the distance decreases. The speed it orbits the Sun must increase because the mass doesn’t change. Just like you saw when you wound the ball around your finger.

Energy is the sum of both the kinetic (moving) energy and the potential energy (this is the “could” energy, as in a
ball dropped from a tower has more potential energy than a ball on the ground, because it “could” move if released). For conservation of energy, as the planet’s distance from the Sun increases, so does the gravitational potential energy. Again, since the energy for the first case must equal the energy from the second case (that’s what conservation means), the kinetic energy must decrease in order to keep the total energy sum a constant value.

Kepler’s 3rd Law is an equation that relates the revolution period with the average orbit speed. The important thing to note here is that mass was not originally in this equation. Newton came along shortly after and did add in the total mass of the system, which fixed the small error with the equation. This makes sense, as you might imagine a Sun twice the size would cause the Earth to orbit faster. However, if we double the mass of the Earth, it does not affect the speed with which it orbits the Sun. Why not? Because the Earth is soooo much smaller than the Sun that increasing a planet’s size generally doesn’t make a difference in the orbital speed. If you’re working with two objects about the same size, of course, then changing one of the masses absolutely has an effect on the other.

Exercises

If the Sun is not stationary in the center but rather gets tugged a couple of feet as the planet yanks on it, how do you think this will affect the planet’s orbit?
If we double the mass of Mars, how do you think this will affects the orbital speed?
If Mercury’s orbit is normally 88 Earth days, how long do you estimate Neptune’s orbit to be?

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Star Wobble

Sunday September 1, 2013

How do astronomers find planets around distant stars? If you look at a star through binoculars or a telescope, you’ll quickly notice how bright the star is, and how difficult it is to see anything other than the star, especially a small planet that doesn’t generate any light of its own! Astronomers look for a shift, or wobble, of the star as it gets gravitationally “yanked” around by the orbiting planets. By measuring this wobble, astronomers can estimate the size and distance of larger orbiting objects.

Doppler spectroscopy is one way astronomers find planets around distant stars. If you recall the lesson where we created our own solar system in a computer simulation, you remember how the star could be influenced by a smaller planet enough to have a tiny orbit of its own. This tiny orbit is what astronomers are trying to detect with this method.

Materials

Several bouncy balls of different sizes and weights, soft enough to stab with a toothpick
Toothpicks

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Does your ball have a number written on it? If so, that’s the weight, and you can skip measuring the weight with a scale.
If not, weigh each one and make a note in the data table.
Take the heaviest ball and spin it on the table. Can you get it to spin in place? That’s like a Sun without any planets around it.
Insert a toothpick into the ball. Now insert the end of the toothpick into the smallest weight ball. Now spin the original ball. What happened?

What’s Going On?

Nearly half of the extrasolar (outside our solar system) planets discovered were found by using this method of detection. It’s very hard to detect planets from Earth because planets are so dim, and the light they do emit tends to be infrared radiation. Our Sun outshines all the planets in our solar system by one billion times.

This method uses the idea that an orbiting planet exerts a gravitational force on the Sun that yanks the Sun around in a tiny orbit. When this is viewed from a distance, the star appears to wobble. Not only that, this small orbit also affects the color of the light we receive from the star. This method requires that scientists make very precise measurements of its position in the sky.

Exercises

For homework tonight, find out how many extrasolar planets scientists have detected so far.
Also for homework, find out the names (they will probably be a string of numbers and letters together) of the 3 most recent extrasolar planet discoveries.

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Eclipses and Transits

Sunday September 1, 2013

It just so happens that the Sun’s diameter is about 400 times larger than the Moon, but the Moon is 400 times closer than the Sun. This makes the Sun and Moon appear to be about the same size in the sky as viewed from Earth. This is also why the eclipse thing is such a big deal for our planet.

You’re about to make your own eclipses as you learn about syzygy. A total eclipse happens about once every year when the Moon blocks the Sun’s light. Lunar eclipses occur when the Sun, Moon, and Earth are lined up in a straight line with the Earth in the. Lunar eclipses last hours, whereas solar eclipses last only minutes.

Materials

2 index cards
Flashlight or Sunlight
Tack or needle
Black paper
Scissors

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Trace the circle of your flashlight on the black paper and cut out the circle with paper. This is your Moon. If you are using the Sun instead, cut out a circle about the size of your fist.
Make a tiny hole in one of the index cards by pushing a tack through the middle of the card.
Hold the punched index card a couple inches above the plain one and shine your light through the hole so that a small disk appears on the lower card. Move the cards closer or further until it comes into focus. The disk of light is the Sun.
Ask your lab partner to slowly move the black paper disk in front of your light as you watch what happens to the Sun on the bottom index card.
Continue moving the black paper until you can see the Sun again.
Where does your circle need to be in order to create an annular eclipse? A partial eclipse?
How would you simulate Mercury transiting the Sun? What would you use?
Fill out the table.

What’s Going On?

An eclipse is when one object completely blocks another. If you’re big on vocabulary words, then let the students know that eclipses are one type of syzygy (a straight line of three objects in a gravitational system, like the Earth, Moon, and Sun). A lunar eclipse is when the Moon moves into the Earth’s shadow, making the Moon appear copper-red.

A solar eclipse is when the Moon’s shadow crawls over the Earth, blocking out the Sun partially or completely. There are three kinds of solar eclipses. A total eclipse blocks the entire Sun, whereas in a partial eclipse the Moon appears to block part, but not all of the Sun’s disk. An annular eclipse is when the Moon is too far from Earth to completely cover the Sun, so there’s a bright ring around the Moon when it moves in front of the Sun. It just so happens that the Sun’s diameter is about 400 times larger than the Moon, but the Moon is 400 times closer than the Sun. This makes the Sun and Moon appear to be about the same size in the sky as viewed from Earth. This is also why the eclipse thing is such a big deal for our planet. Transits are where the disk of a planet (like Venus) passes like a small shadow across the Sun. Io transits the surface of Jupiter. In rare cases, one planet will transit another. These are rare because all three objects must align in a straight line.

Astronomers use this method to detect large planets around distant bright stars. If a large planet passes in front of its star, the star will appear to dim slightly. Note: A transit is not an occultation, which completely hides the smaller object behind a larger one. Exercises

What other planets can have eclipses?
Which planets transit the Sun?
How is a solar eclipse different from a lunar eclipse?
What phase can a lunar eclipse occur?
Can a solar eclipse occur at night?

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Meteorites

Sunday September 1, 2013

A meteoroid is a small rock that zooms around outer space. When the meteoroid zips into the Earth’s atmosphere, it’s now called a meteor or “shooting star”. If the rock doesn’t vaporize en route, it’s called a meteorite as soon as it whacks into the ground. The word meteor comes from the Greek word for “high in the air.”

Meteorites are black, heavy (almost twice the normal rock density), and magnetic. However, there is an Earth-made rock that is also black, heavy, and magnetic (magnetite) that is not a meteorite. To tell the difference, scratch a line from both rocks onto an unglazed tile. Magnetite will leave a mark whereas the real meteorite will not.

Materials

White paper
Strong magnet
Handheld magnifying glass (optional)

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Imagine you are going on a rock hunt. You are to find which rocks are meteorites and which are Earth rocks. If you don’t have access to rock samples, just watch the experiment video of the different rock samples. If you’d like to make your own sample collection, here are some ideas:
1. 8-10 different rocks, including pumice (from a volcano), lodestone (a naturally magnetized piece of magnetite, and often mistaken for meteorites), a fossil, tektite (dry fused glass), pyrite (also known as fool’s gold), marble (calcite or dolomite), and a couple of different kinds of real meteorites (iron meteorite, stony meteorite, etc.) Also add to your bag an unglazed tile and a magnet.
As you watch the experiment video, record your observations on your data sheet.
1. Since nearly all meteorites have lots of iron, they are usually attracted to a magnet. However, lodestone is an Earth rock that also has a lot of iron. Iron is heavy, and meteorites contain a lot of iron. When looking through the possibilities, remove any lightweight rocks, as they are not usually meteorites.
2. Meteorites are small. Most never get big enough or hot enough for metal to sink into the core, so the majority are mixed with rock and dust (stony meteorites). The few that do get big and form metal cores are called iron meteorites.
3. Most meteorites come from the Asteroid Belt. Some meteorites get a dark crust. While others look like splashed metal. They are all dark, at least on the outside. Remove any light-colored rocks.
4. Rocks that have holes vaporize or explode when they go through the atmosphere, they don’t burn up. Only strong space rocks without holes make it to the ground. Remove any porous rocks.
5. The ones you have left are either meteorites or lodestone. To tell the difference, scratch a line from both rocks onto an unglazed tile. Magnetite (lodestone) will leave a mark whereas the real meteorite will not.

Finding Meteorites

Place a sheet of white paper outside on the ground. Do this in the morning when you first start up class.
After a few hours (like just before lunchtime), your paper starts to show signs of “dust.”
Carefully place a magnet underneath the paper, and see if any of the particles move as you wiggle the magnet. If so, you’ve got yourself a few bits of space dust.
Use a magnifying lens to look at your space meteorites up close.

What’s Going On?

94% of all meteorites that fall to the Earth are stony meteorites. Stony meteorites will have metal grains mixed with the stone that are clearly visible when you look at a slice.

Iron meteorites make up only 5% of the meteorites that hit the Earth. However, since they are stronger, most of them survive the trip through the atmosphere and are easier to find since they are more resistant to weathering. More than half the meteorites we find are iron meteorites. They are the one of the densest materials on Earth. They stick strongly to magnets and are twice as heavy as most Earth rocks. The Hoba meteorite in Namibia weighs 50 tons.

Since nearly all meteorites have lots of iron, they are usually attracted to a magnet. However, lodestone is an Earth rock that also has a lot of iron. Iron is heavy, and meteorites contain a lot of iron. When looking through the possibilities, remove any lightweight rocks, as they are not usually meteorites.

Meteorites are small. Most never get big enough or hot enough for metal to sink into the core, so the majority are mixed with rock and dust (stony meteorites). The few that do get big and form metal cores are called iron meteorites.

Most meteorites come from the Asteroid Belt. Some meteorites get a dark crust, while others look like splashed metal. They are all dark, at least on the outside.

Rocks that have holes vaporize or explode when they go through the atmosphere, they don’t burn up. Only strong space rocks without holes make it to the ground.

Every year, the Earth passes through the debris left behind by comets. Comets are dirty snowballs that leave a trail of particles as they orbit the Sun. When the Earth passes through one of these trails, the tiny particles enter the Earth’s atmosphere and burn up, leaving spectacular meteor showers for us to watch on a regular basis. The best meteor showers occur when the moon is new and the sky is very dark.

Meteorites are black, heavy (almost twice the normal rock density), and magnetic. However, there is an Earth-made rock that is also black, heavy, and magnetic (magnetite) that is not a meteorite. To tell the difference, scratch a line from both rocks onto an unglazed tile (or the bottom of a coffee mug or the underside of the toilet tank). Magnetite will leave a mark, whereas the real meteorite will not.

If you find a meteorite, head to your nearest geology department at a local university or college and let them know what you’ve found. In the USA, if you find a meteorite, you get to keep it… but you might want to let the experts in the geology department have a thin slice of it to see what they can figure out about your particular specimen.

Exercises

Are meteors members of the solar system?
How big are meteors?
Why do we have meteor showers at predictable times of the year?

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Solar Rotation

Sunday September 1, 2013

You are going to start observing the Sun and tracking sunspots across the Sun using one of two different kinds of viewers so you can figure out how fast the Sun rotates. Sunspots are dark, cool areas with highly active magnetic fields on the Sun’s surface that last from hours to months. They are dark because they aren’t as bright as the areas around them, and they extend down into the Sun as well as up into the magnetic loops.

Materials

Tack and 2 index cards OR a Baader film (this works better than the tacks and card)

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We’re going to learn two different ways to view the Sun. First is the pinhole projector and the second is using a special film called a Baader filter. The quickest and simplest way to do this is to build a super-easy pinhole camera that projects an image of the Sun onto an index card for you to view.

If the Sun is not available, you can use images from a satellite that’s pointed right at the Sun while orbiting around the Earth called “SOHO.” SOHO gets clear, unobstructed views of the Sun 24 hours a day, since it’s above the atmosphere of the Earth. Download the very latest image of the Sun from NASA’s SOHO page (choose the SDO/HMI Continuum filter for the best sunspot visibility) and hand them out to the students to track the sunspots.

Solar Pinhole Projector

With your tack, make a small hole in the center of one of the cards.
Stack one card about 12″ above the other and go out into the Sun.
Adjust the spacing between the cards so a sharp image of the Sun is projected onto the lower paper.
The Sun will be about the size of a pea.
You can experiment with the size of the hole you use to project your image.
What happens if your hole is really big? Too small?
What if you bend the lower card while viewing? What if you punch two holes? Or three?

Baader Filter

Using a Baader filter, you’re going to look straight through the filter right at the Sun. Put the filter between you and the Sun, right up close to your eye and look through it. It takes a little while to get the hang of seeing the Sun through this filter, but it’s totally worth it.

Taking Data:

Using either the Baader filter or the solar pinhole projector (or both), you will track the sunspot activity using the mapping grid. You will be charting the Sun for two weeks using the mapping grid.
Each day, step outside at the same time each day and look at the Sun using one of the two filter methods.
Draw what you see on the mapping grid.
Draw the sunspot(s) with the date of the month next to it. For example, on March 13, write a “13” right next to the sunspot picture you drew. If there’s more than one sunspot, pick the largest one to track. If you’d like to track all of them, label them A-13, B-13, C-13…etc. The next day, label the set A-14, B-14, C-14. For multiple sunspots, use one mapping grid per day.

What’s Going On?

The Sun rotates differentially, since it’s not solid but rather a ball of hot gas and plasma. The equator rotates faster than the poles, and in one of the experiments in this section, you’ll actually get to measure the Sun’s rotation. This differential rotation causes the magnetic fields to twist and stretch. The Sun has two magnetic poles (north and south) that swap every 11 years as the magnetic fields reach their breaking point, like a spinning top that’s getting tangled up in its own string. When they flip, it’s called “solar maximum,” and you’ll find the most sunspots dotting the Sun at this time.

You know you’re not supposed to look at the Sun, so how can you study it safely? I’m going to show you how to observe the Sun safely using a very inexpensive filter. I actually keep one of these in the glove box of my car so I can keep track of certain interesting sunspots during the week!

The visible surface of the Sun is called the photosphere, and is made mostly of plasma (electrified gas) that bubbles up hot and cold regions of gas. When an area cools down, it becomes darker (called sunspots). Solar flares (massive explosions on the surface), sunspots, and loops are all related the Sun’s magnetic field. While scientists are still trying to figure this stuff out, here’s the latest of what they do know…

The Sun is a large ball of really hot gas – which means there are lots of naked charged particles zipping around. And the Sun also rotates, but the poles and the equator move and different speeds (don’t forget – it’s not a solid ball but more like a cloud of gas). When charged particles move, they make magnetic fields (that’s one of the basic laws of physics). And the different rotation rates allow the magnetic fields to “wind up” and cause massive magnetic loops to eject from the surface, growing stronger and stronger until they wind up flipping the north and south poles of the Sun (called ‘solar maximum’). The poles flip every 11 years.

The Sun rotates, but because it’s not a solid body but a big ball of gas, different parts of the Sun rotate at different speeds. The equator (once every 27 days) spins faster than the poles (once every 31 days). Sunspots are a great way to estimate the rotation speed.

Sunspots usually appear in groups and can grow to several times the size of the Earth. Galileo was the first to record solar activity in 1613, and was amazed how spotty the Sun appeared when he looked at the projected image on his table.

There have been several satellites especially created to observe the Sun, including Ulysses (launched 1990, studied solar wind and magnetic fields at the poles), Yohkoh (1991-2001, studied X-rays and gamma radiation from solar flares), SOHO (launched 1995, studies interior and surface), and TRACE (launched 1998, studies the corona and magnetic field). And as of August 2017, Astronomers have figured out that the surface of the sun rotates slower than its core (by about four times as much!) by studying surface acoustic waves in the sun’s atmosphere.

Exercises

How many longitude degrees per day does the sunspot move?
Do all sunspots move at the same rate?
Did some of the sunspots change size or shape, appear or disappear?

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Sky in a Jar

Sunday September 1, 2013

Have you ever wondered why the sky is blue? Or why the sunset is red? Or what color our sunset would be if we had a blue giant instead of a white star? This lab will answer those questions by showing how light is scattered by the atmosphere.

Particles in the atmosphere determine the color of the planet and the colors we see on its surface. The color of the star also affects the color of the sunset and of the planet.

Materials

Glass jar
Flashlight
Fingernail polish (red, yellow, green, blue)
Clear tape
Water
Dark room
Few drops of milk

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Make your room as dark as possible for this experiment to work.
Make sure your label is removed from the glass jar or you won’t be able to see what’s going on.
Fill the clear glass jar with water.
Add a teaspoon or two of milk (or cornstarch) and swirl.
Shine the flashlight down from the top and look from the side – the water should have a bluish hue. The small milk droplets scatter the light the same way our atmosphere’s dust particles scatter sunlight.
Try shining the light up from the base – where do you need to look in order to see a faint red/pink tint? If not, it’s because you are looking for hues that match our real atmosphere, and the jar just isn’t that big, nor is your flashlight strong enough! Instead, look for a very slight color shift. If you do this experiment after being in the dark for about 10 minutes (letting your eyes adjust to the lack of light), it is easier to see the subtle color changes. Just be careful that you don’t let the brilliant flashlight ruin your newly acquired night-vision, or you’ll have to start the 10 minutes all over again.
If you are still having trouble seeing the color changes, shine your light through the jar and onto an index card on the other side. You should see slight color changes on the white card.
Cover the flashlight lens with clear tape.
Paint on the tape (not the lens) the fingernail polish you need to complete the table.
Repeat steps 7-9 and record your data.

What’s Going On?

Why is the sunset red? The colors you see in the sky depends on how light bounces around. The red/orange colors of sunset and sunrise happen because of the low angle the Sun makes with the atmosphere, skipping the light off dust and dirt (not to mention solid aerosols, soot, and smog). Sunsets are usually more spectacular than sunrises, as more “stuff” floats around at the end of the day (there are less particles present in the mornings). Sometimes just after sunset, a green flash can be seen ejecting from the setting Sun.

The Earth appears blue to the astronauts in space because the shorter, faster wavelengths are reflected off the upper atmosphere. The sunsets appear red because the slower, longer wavelengths bounce off the clouds.Sunsets on other planets are different because they are farther (or closer) to the Sun, and also because they have a different atmosphere than planet Earth. The image shown here is a sunset on Mars. Uranus and Neptune appear blue because the methane in the upper atmosphere reflects the Sun’s light and the methane absorbs the red light, allowing blue to bounce back out.

Exercises

What colors does the sunset go through?
Does the color of the light source matter?

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Black Hole Bucket

Sunday September 1, 2013

What comes to mind when you think about empty space? (You should be thinking: “Nothing!”) One of Einstein’s greatest ideas was that empty space is not actually nothing – it has energy and can be influenced by objects in it. It’s like the T-shirt you’re wearing. You can stretch and twist the fabric around, just like black holes do in space.

Today, you will get introduced to the idea that gravity is the structure of spacetime itself. Massive objects curve space. How much space curves depends on how massive the object is, and how far you are from the massive object.

Materials

Two buckets with holes in the bottom
2 bungee cords
3 different sizes of marbles
2.5 lb weight
0.5 lb weight
3 squares of stretchy fabric
Rubber band
4 feet of string
Fishing bobber
Drinking straws
Softball
Playdough (optional)

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Making the Buckets Ready for the Lab

What is gravity? How does it work? That’s what today’s lab is all about.
Stretch the bungee cord around the circumference of the bucket. Do this for both buckets.
On one bucket, tuck in the stretchy fabric under the cord. If your cords are loose, tie another knot near the end so they fit snugly around the bucket. The fabric is stretched like a drum head. This is the “fabric of space” – it’s around us everywhere.
Push the bottom of the bobber so the hook opens on the other end. Push your string in.
Place it in the center of the squares of fabric. Fasten it with your rubber band.
Thread the ends of your string through the bottom holes of your second bucket and tie it securely on the bottom.
Tuck in your corners under the bungee cord. This is your black hole bucket.
The first lab uses two buckets, neither of which is a black hole. We’re going to convert the black hole bucket to a regular spacetime fabric bucket. For now, place a second piece of fabric over the black hole bucket and tuck it under the cord so that it looks like the first bucket you used.
Now, we’re ready for our lab.

Exploring How Space Curves

Place a mid-sized weight in the middle of one of the buckets. What happens to the fabric when you put a weight on the fabric?
Place the heavy 2.5lb lead weight in the center of the fabric of the second bucket. Did it curve more or less than the first weight?
The heavier weight is like the Sun, and the lighter weight is like the Earth. Which has more mass?
Which has more gravitational attraction?
Is space more or less curved further from the object?
Where is space curved the most?
Grab your marbles. These are your space probes. If we place one probe at the edge of each bucket, which do you expect it to fall toward the middle faster?
Why?
This is what we mean when we say the force of gravity depends on how much mass something has, since mass curves space. More massive objects curve space more, so the gravitational attraction is more with more massive objects.
Take two marbles of different sizes and drop them at the same time onto the edge of the bucket. You can drop them on opposite sides so they don’t knock into each other. What happens?
The Moon is like a giant marble. Why doesn’t it fall to Earth?
Why is it orbiting?
Remove all weights from the fabric. Roll a marble across the surface (do it slowly without bouncing – planet’s don’t bounce!). Does it roll straight or curved?
Place the heavy weight on the fabric. Try to make the marble go in a straight line. Did it work?
Can you roll the marble so that it escapes from the weight that represents the Sun?
In the second bucket, place a smaller weight and do steps 23 and 24 again. How is this different?
Planets orbit the Sun because space is curved around the Sun. The Moon orbits the Earth without falling in because space is curved around Earth. How fast the moon moves through space and how much the Earth curves space depends on the Earth’s mass and how far away the moon is.
If the Moon was in closer to the Earth, would it have to move faster or slower to maintain its orbit?
Let’s find out: Place two marbles, one closer to the weight and one near the edge of the bucket, and make them orbit the weight. Which one orbits faster? Why?
Replace the weight in the second bucket with a lightweight mass. Now, what if Earth was less massive? How would this change the Moon’s orbit?
Notice this: When you roll a ball in orbit around a weight, do you see the weight move slightly also? All orbiting objects yank on each other. The Moon pulls on the Earth just as the Earth pulls on the Moon. All massive objects cause space to move: planets, stars, black holes, comets, etc.

Exploring Black Holes

Place a weight in each bucket, one representing the Earth and the other representing the Moon.
Place a marble next to each weight. These marbles are your rocket ships. Do you think that you can launch your rockets and escape the pull of gravity? Grab a straw and try to blow the marble away from the weight (launch the rocket off the Earth and moon). What happened? Why?
What if we start the rockets in space? Do you think you can escape the pull of the objects now? Start the marbles orbiting and then blow them the straws. Can you fire your rockets at the right time to get your rockets to escape the orbit?
Let’s launch a probe out of a black hole! Remove the fabric from the black hole bucket and place a marble in the black hole. Can you use your straw to blow the marble out of the black hole?
Let’s see the difference between the Sun and a black hole. Grab an 8-ounce weight and the softball. These have the same mass, but they are different sizes. The softball is the Sun, and the weight is the black hole. Which is going to curve space more when you place it on the fabric? Guess before you try it:
Replace the fabric over the black hole bucket.
Place the softball on one of the buckets, and the 8-ounce weight on the other bucket.
Roll a marble near the edge of each bucket. This is where our Earth would be orbiting. Notice that although the weight curves space more near it, at the edge, the curvature is the same. So if the Sun were suddenly replaced by a black hole of the same mass, the Earth wouldn’t notice it (gravitationally, at least. It would get dark and cold, though.),
Remove the second fabric from the black hole bucket so you have the vortex exposed.
Take two marbles and start them orbiting at the edge of the black hole. What happens? Why?
Make a rocket shape out of clay or playdough. Bring the rocket close to the black hole bucket and get prepared to show your teammates what happens if it goes into the black hole. First, it stretches (pull the rocket into a longer shape), then it gets shredded (crumple it up) and finally added to the black hole’s mass (shove it into the bucket).

What’s Going On?

Massive objects are truly massive. If our solar system was the size of a quarter, the Milky Way would be the size of North America.

The Milky Way has an estimated 100 billion stars. That’s hard to imagine, so try this: Imagine a football field piled 4’ deep in birdseed. Now scatter those seeds over North America and space them 25 miles deep. Each seed is a Sun. Stars are very far apart!

If the mass of the Sun was one birdseed, then the mass of a black hole would be 22 gallons of birdseed shoved into the volume of a single birdseed.

It’s time to explore how black holes interact with the universe. There are four animations to watch. Let the students know that these are scientific simulations which used actual data to create them – they are not artist’s concepts or fantasy. They are based on solid physics. The reason they are animations is because these videos happen over such a long period of time, and our view is limited in some cases.

Exercises

What is the event horizon?
Does a more massive object curve space more or less than a smaller object? What does this mean for the gravitational field?
Does an object feel more or less gravitational attraction as the object moves closer to a massive object?
Where is space most curved?
What is mass?

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Planetary Magnetic Fields

Sunday September 1, 2013

You’re going to use a compass to figure out the magnetic lines of force from a magnet by mapping the two different poles and how the lines of force connect the two. A magnetic field must come from a north pole of a magnet and go to a south pole of a magnet (or atoms that have turned to the magnetic field.)

Compasses are influenced by magnetic lines of force. These lines are not necessarily straight. When they bend, the compass needle moves. The Earth has a huge magnetic field. The Earth has a weak magnetic force. The magnetic field comes from the moving electrons in the currents of the Earth’s molten core. The Earth has a north and a south magnetic pole which is different from the geographic North and South Pole.

Materials

Bar magnet
Horseshoe magnet
Circular (disk) magnet
Compass
String
Ruler

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Tie a string around your magnet.
Bring it close to the compass.
Which end is the north end of your magnet? Label it with a pencil right on the magnet.
Flip the magnet around by twisting the string so that the compass flips to the opposite pole. Label the opposite site of the magnet with the appropriate letter (N or S).
Bring a second magnet close to the first one. What happens when you bring two opposite poles together? What if the poles are the same?
Now untie or cut the string for the next part of your lab.
Lay a piece of paper on your desk.
Place the magnet in the middle of the paper and trace the outline.
Draw 12 dots (just like on a clock) all the way around the magnet. These are the locations where you will place your compass, so make sure that they are close enough to the magnet so the magnet influences the compass.
Place your compass on one of the dots and look at the direction the arrow is pointing. Remove the compass and draw that exact arrow direction right over your dot. Do this for all 12 dots.
Draw another ring of dots an inch or two out from the first ring and repeat step 9.
Repeat steps 6-10 with a circular magnet on a new sheet of paper.
Repeat steps 6-10 for the horseshoe magnet on another sheet of paper.

What’s Going On?

Right under your feet, there’s a magnet. Go ahead take a look. Lift up your feet and see what’s under there. Do you see it? It’s huge! In fact, it’s the largest magnet on the Earth. As a matter of fact, it is the Earth! That’s right; the Earth is one huge, gigantic, monolithic magnet! We’re going to use a magnet to substitute for the Earth and plot out the magnetic field lines.

The magnetic pole which was attracted to the Earth’s North Pole was labeled as the Boreal or “north-seeking pole” in the 1200s, which was later shortened to “north pole.” To add to the confusion, geologists call this pole the North Magnetic Pole.

Exercises

How are the lines of force different for the two magnets?
How far out (in inches measured from the magnet) does the magnet affect the compass?
What makes the compass move around?
Do you think the compass’s north–south indicator is flipped, or the Earth’s North Pole where the South Pole is? How do you know?

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Binary Planetary Systems

Sunday September 1, 2013

A binary system exists when objects approach each other in size (and gravitational fields), the common point they rotate around (called the center of mass) lies outside both objects and they orbit around each other. Astronomers have found binary planets, binary stars, and even binary black holes.

The path of a planet around the Sun is due to the gravitational attraction between the Sun and the planet. This is true for the path of the Moon around the Earth, and Titan around Saturn, and the rest of the planets that have an orbiting moon.

Materials

Soup cans or plastic containers with holes punched (like plastic yogurt containers, butter tubs, etc.)
String
Water
Sand
Rocks
Pebbles
Baking soda
Vinegar

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Thread one end of the string through one of the holes and tie a strong knot. Really strong.
Tie the other end through the other hole and tie off.
Go outside.
Fill your can partway with water.
Move away from everyone before you start to swing your container in a gentle circle. As you spin faster and faster, notice where the water is inside the container.
Now empty out the water and replace it with rocks. Spin again and fill out the data table.
To make carbon dioxide gas, you’ll need to work with another lab team. Cover the bottom of your container with baking soda. Add enough vinegar so that the bubbles reach the top without overflowing. Wait patiently for the bubbles to subside. You now have a container filled with carbon dioxide gas (and a little sodium acetate, the leftovers from the reaction). Carefully pour this into the empty container from the other lab team. They can spin again and record their results. When they are done, borrow their container and give them yours so they can fill it for you.

What’s Going On?

Charon and Pluto orbit around each other due to their gravitational attraction to each other. However, Charon is not the moon of Pluto, as originally thought. Pluto and Charon actually orbit around each other. Pluto and Charon also are tidally locked, just like the Earth-Moon system, meaning that one side of Pluto is always faces the same side of Charon.

Imagine you have a bucket half full of water. Can you tilt a bucket completely sideways without spilling a drop? Sure thing! You can swing it by the handle, and even though it’s upside down at one point, the water stays put. What’s keeping the water inside the bucket?

Before we answer this, imagine you are a passenger in a car, and the driver is late for an appointment. They take a turn a little too fast, and you forgot to fasten your seat belts. The car makes a sharp left turn. Which way would you move in the car if they took this turn too fast? Exactly – you’d go sliding to the right. So, who pushed you?

No one! Your body wanted to continue in a straight line, but the car is turning, so the right side car door keeps pushing you to turn you in a curve – into the left turn. The car door keeps moving in your way, turning you into a circle. The car door pushing on you is called centripetal force. Centripetal means “center-seeking.” It’s the force that points toward the center of the circle you’re moving on. When you swing the bucket around your head, the bottom of the bucket is making the water turn in a circle and not fly away. Your arm is pulling on the handle of the bucket, keeping it turning in a circle and not letting it fly away. That’s centripetal force.

Think of it this way: If I throw a ball in outer space, does it go in a straight line or does it wiggle all over the place? Straight line, right? Centripetal force is the force needed to keep an object following a curved path.

Remember how objects will travel in a straight line unless they bump into something or have another force acting on them, such as gravity, drag force, and so forth? Well, to keep the bucket of water swinging in a curved arc, the centripetal force can be felt in the tension experienced by the handle (or your arm, in our case). Swinging an object around on a string will cause the rope to undergo tension (centripetal force), and if your rope isn’t strong enough, it will snap and break, sending the mass flying off in a tangent (straight) line until gravity and drag force pull the object to a stop. This force is proportional to the square of the speed – the faster you swing the object, the higher the force.

Exercises

How is spinning the container like Pluto and Charon?
What would happen if we cut the string while you are spinning? Which way would the container go?
What happens if we triple the size of your container and what’s inside of it?

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Seasons

Sunday September 1, 2013

One common misconception is that the seasons are caused by how close the Earth is to the Sun. Today you get to do an experiment that shows how seasons are affected by axis tilt, not by distance from the Sun. And you also find out which planet doesn’t have sunlight for 42 years.

The seasons are caused by the Earth’s axis tilt of 23.4o from the ecliptic plane.

Materials

Bright light source (not fluorescent)
Balloon
Protractor
Masking tape
2 liquid crystal thermometers (optional)
Ruler, yardstick or meter stick
Marker

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For a light source, try lamps with 100W bulbs (without lamp shades). Make sure there’s room to walk all the way around it. You’ll want to circle the lamp at a distance of about 2 feet away.
Mark on the floor with tape and label the four positions: winter, spring, summer, and fall. They should be at the 12, 3, 6, and 9 o’clock positions. Winter is directly across from summer. The Earth rotates counterclockwise around the Sun when viewed from above.
Blow up your balloon so it’s roughly round-shaped (don’t blow it up all the way). Mark and label the north and south poles with your marker. Draw an equator around the middle circumference.
The Earth doesn’t point its north pole straight up as it goes around the Sun. It’s tilted over 23.4o. here’s how you find this point on your balloon:
1. Put the South Pole mark on the table, with north pointing straight up. Find the midway point between the equator and the North Pole and make a tiny mark. This is the 45o latitude point. You’ll need this to find the 23o mark.
2. Find the midway point between the 45o and the North Pole and make another mark, larger this time and label it with 23o. When this mark is pointing up, the Earth is tilted over the right amount.
3. You’ll need to do this three more times so you can draw a line connecting the dots. You want to draw the latitude line at 23o so you can rotate the balloon as you move around to the different seasons. The line will always be pointed up.
Place the thermometers on the balloon at these locations:
1. Find the halfway point between the South Pole and the equator. Put one thermometer on this mark.
2. Put the other thermometer on the northern hemisphere’s 45o mark from above.
Make sure your lamp is facing the balloon as you stand on summer. Let the balloon be heated by the lamp for a couple of minutes and then record the temperature in the data table.
Rotate the lamp to point to fall. Move your balloon to fall, rotating the balloon so that the thermometers are facing the lamp. Wait a few more minutes and take another reading.
Rotate the lamp to point to winter. Move your balloon to winter, rotating the balloon so that the thermometers are facing the lamp. Wait a few more minutes and take another reading.
Rotate the lamp to point to spring. Move your balloon to spring, rotating the balloon so that the thermometers are facing the lamp. Wait a few more minutes and take another reading. You’ve completed a data set for planets with an axis tilt of about 23o, which includes the Earth, Mars, Saturn and Neptune.
Repeat steps 1-9 for Mercury. Note that Mercury does not have an axis tilt, so the North Pole really points straight up. Jupiter (3.1o axis tilt) and Venus (2.7o) are very similar. The Moon’s axis tilt is 6.7o, so you can approximate these four objects with a 0o axis tilt.
Repeat steps 1-9 for Uranus. Since the axis tilt is 97.8o, you can approximate this by pointing the north pole straight at the Sun during summer (90o axis tilt). The orbit for Uranus is 84 years, which means 21 years passes between each season. The north pole will experience continued sunlight for 42 years from spring through fall, then darkness for 42 years.

What’s Going On?

The north and south poles only experience two seasons: winter and summer. During a South Pole winter, the Sun will not rise for several months, and also the Sun does not set for several months in the summer. We go into more detail about how this works in a later lesson entitled: Star Trails and Planet Patterns.

At the equator, there’s a wet season and a dry season due to the tropical rain belt. Since the equator is always oriented at the same position to the Sun, it receives the same amount of sunlight and always feels like summer.

The changing of the seasons is caused by the angle of the Sun. For example, in June during summer solstice, the Sun is high in the sky for longer periods of time, which makes warmer temperatures for the Northern Hemisphere. During the December winter solstice, the Sun spends less time in the sky and is positioned much lower. This makes the winters colder. (Don’t forget that seasons are also affected by oceans and winds, though this is out of the scope of this particular activity.)

Exercises

What is the main reason we have seasons on Earth?
Why are there no sunsets on Uranus for decades?
Are there seasons on Venus?

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Watch Your Weight

Sunday September 1, 2013

If you could stand on the Sun without being roasted, how much would you weigh? The gravitational pull is different for different objects. Let’s find out which celestial object you’d crack the pavement on, and which your lightweight toes would have to be careful about jumping on in case you leapt off the planet.

Weight is nothing more than a measure of how much gravity is pulling on you. Mass is a measure of how much stuff you’re made out of. Weight can change depending on the gravitational field you are standing in. Mass can only change if you lose an arm.

Materials

Scale to weigh yourself
Calculator
Pencil

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Download Student Worksheet & Exercises

We need to talk about the difference between weight and mass. In everyday language, weight and mass are used interchangeably, but scientists know better.
Mass is how much stuff something is made out of. If you’re holding a bowling ball, you’ll notice that it’s hard to get started, and once it gets moving, it needs another push to get it to stop. If you leave the bowling ball on the floor, it stays put. Once you push it, it wants to stay moving. This “sluggishness” is called inertia. Mass is how much inertia an object has.
Every object with mass also has a gravitational field, and is attracted to everything else that has mass. The amount of gravity something has depends on how far apart the objects are. When you step on a bathroom scale, you are reading your weight, or how much attraction is between you and the Earth.
If you stepped on a scale in a spaceship that is parked from any planets, moons, black holes, or other objects, it would read zero. But is your mass zero? No way. You’re still made of the same stuff you were on Earth, so your mass is the same. But you’d have no weight.
What is your weight on Earth? Let’s find out now.
Step on the scale and read the number. Write it down.
Now, what is your weight on the Moon? The correction factor is 0.17. So multiply your weight by 0.17 to find what the scale would read on the Moon.
For example, if I weigh 100 pounds on Earth, then I’d weight only 17 pounds on the Moon. If the scale reads 10 kg on Earth, then it would read 1.7 kg on the Moon.

What’s Going On?

Weight is nothing more than a measure of how much gravity is pulling on you. This is why you can be “weightless” in space. You are still made of stuff, but there’s no gravity to pull on you so you have no weight. The larger a body is, the more gravitational pull (or in other words the larger a gravitational field) it will have.

The Moon has a fairly small gravitational field (if you weighed 100 pounds on Earth, you’d only be 17 pounds on the Moon).The Earth’s field is fairly large and the Sun has a HUGE gravitational field (if you weighed 100 pounds on Earth, you’d weigh 2,500 pounds on the Sun!).

As a matter of fact, the dog and I both have gravitational fields! Since we are both bodies of mass, we have a gravitational field which will pull things toward us. All bodies have a gravitational field. However, my mass is so small that the gravitational field I have is miniscule. Something has to be very massive before it has a gravitational field that noticeably attracts another body.

So what’s the measurement for how much stuff you’re made of? Mass. Mass is basically a weightless measure of how much matter makes you you. A hamster is made of a fairly small amount of stuff, so she has a small mass. I am made of more stuff, so my mass is greater than the hamster’s. Your house is made of even more stuff, so its mass is greater still. So, here’s a question. If you are “weightless” in space, do you still have mass? Yes, the amount of stuff you’re made of is the same on Earth as it is in your space ship. Mass does not change, but since weight is a measure for how much gravity is pulling on you, weight will change.

Did you notice that I put weightless in quotation marks? Wonder why?

Weightlessness is a myth! Believe it or not, one is never weightless. A person can be pretty close to weightless in very deep space, but the astronauts in a space ship actually do have a bit of weight.

Think about it for a second. If a space ship is orbiting the Earth, what is it doing? It’s constantly falling! If it wasn’t moving forward at tens of thousands of miles an hour it would hit the Earth. It’s moving fast enough to fall around the curvature of the Earth as it falls but, indeed, it’s falling as the Earth’s gravity is pulling it to us.

Otherwise the ship would float out to space. So what is the astronaut doing? She’s falling, too! The astronaut and the space ship are both falling to the Earth at the same rate of speed and so the astronaut feels weightless in space. If you were in an elevator and the cable snapped, you and the elevator would fall to the Earth at the same rate of speed. You’d feel weightless! (Don’t try this at home!)

Either now, or at some point in the future you may ask yourself this question, “How can gravity pull harder (put more force on some things, like bowling balls) and yet accelerate all things equally?” When we get into Newton’s laws in a few lessons, you’ll realize that doesn’t make any sense at all. More force equals more acceleration is basically Newton’s Second law.

Well, I don’t want to take too much time here since this is a little deeper then we need to go but I do feel some explanation is in order to avoid future confusion. The explanation for this is inertia. When we get to Newton’s First law we will discuss inertia. Inertia is basically how much force is needed to get something to move or stop moving.

Now, let’s get back to gravity and acceleration. Let’s take a look at a bowling ball and a golf ball. Gravity puts more force on the bowling ball than on the golf ball. So the bowling ball should accelerate faster since there’s more force on it. However, the bowling ball is heavier so it is harder to get it moving. Vice versa, the golf ball has less force pulling on it but it’s easier to get moving. Do you see it? The force and inertia thing equal out so that all things accelerate due to gravity at the same rate of speed!

Gravity had to be one of the first scientific discoveries. Whoever the first guy was to drop a rock on his foot, probably realized that things fall down! However, even though we have known about gravity for many years, it still remains one of the most elusive mysteries of science. At this point, nobody knows what makes things move toward a body of mass.

Why did the rock drop toward the Earth and on that guy’s foot? We still don’t know. We know that it does, but we don’t know what causes a gravitational attraction between objects. Gravity is also a very weak force. Compared to magnetic forces and electrostatic forces, the gravitational force is extremely weak. How come? No one knows. A large amount of amazing brain power is being used to discover these mysteries of gravity. Maybe it will be you who figures this out!

Exercises

Of the following objects, which ones are attracted to one another by gravity?
a) Apple and Banana b) Beagle and Chihuahua c) Earth and You d) All of the above
True or False: Gravity accelerates all things differently
True or False: Gravity pulls on all things differently
If I drop a golf ball and a golf cart at the same time from the same height, which hits the ground first?
There is a monkey hanging on the branch of a tree. A wildlife biologist wants to shoot a tranquilizer dart at the monkey to mark and study him. The biologist very carefully aims directly at the shoulder of the monkey and fires. However, the gun makes a loud enough noise that the monkey gets scared, lets go of the branch and falls directly downward. Does the dart hit where the biologist was aiming, or does it go higher or lower then he aimed? (This, by the way, is an old thought problem.)

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Star Gazing

Sunday September 1, 2013

Telescopes and binoculars are pretty useless unless you know where to point them. I am going to show you some standard constellations and how to find them in the night sky, so you’ll never be lost again in the ocean of stars overhead. We’re going to learn how to go star gazing using planetarium software, and how to customize to your location in the world so you know what you’re looking at when you look up into the sky tonight!
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Materials: You’ll need to download and install Stellarium Planetarium Software before watching the video below. If you need a paper planetarium, try downloading this star wheel from Sky & Telescope here or try this simple star wheel here.

Click to download the student worksheet.

You’re about to locate several different celestial objects by first finding them in your planetarium software (or after assembling your star wheel).

UPDATE! There’s a complete STARGAZING set of lessons now available! Go here to find the new STARGAZING LESSONS!

If you haven’t already, customize your planetarium software to your location by entering in your location and elevation.
Now adjust the time so that it’s set to the time you’d like to star gaze tonight. What time will you star gaze tonight? Write this in your science notebook.
For folks in the Northern Hemisphere, find the Big Dipper. For Southern Hemisphere folks, find the Southern Cross (or the Crux, but it really looks like a big kite). These are one of the most recognizable patterns, and easy for beginners to find.
For Northerners, use the Big Dipper to locate Polaris, the North Star. The two stars at the edge of the dipper point straight to the North Star. (Refer to top image.)
For Southerners, use the Southern Cross to find the south pole of the sky (sometimes called the “south pole pit” since there’s no star there at the exact pole point of the southern sky). The longer bar in the cross points almost exactly toward the South Pole. (Refer to bottom image.)
Using the Search option, find the planets that will be visible tonight by typing in their name into the search window. Which ones will be visible for you tonight? Write this in your science notebook.
In Stellarium, click the “Search” icon, then the “Lists” tab, and select “Constellations”. Select two different constellations you’d like to find tonight that are visible to you, and record information about them on a piece of paper so you have it with you tonight. Include information about how you’ll find it (for example, what is it next to?)
When you’re ready, flip open your science notebook to the page with what you’re planning to look at, grab a a flashlight, pencil, and then go outside to log your observations, just like a real scientist!

Observing Tip: Try to observe when the moon is less than first quarter phase or more than three quarters (meaning that the moon is less than 50% illuminated). You don’t need any fancy viewing equipment, only your science notebook, and if you can do it, bring your planetarium software program with you outside to help you locate the objects. Start small, and find a couple of things on the first night. If you don’t figure it out the first time, try again the next night. I learned the northern sky by learning one new constellation every time I went star gazing, and pretty soon I had a lot of them that I could identify easily.

Note: This isn’t something that’s going to work by osmosis. You will have to go outside, figure out where to look, and find the object. Figure out what you’re looking for, and about where you can expect to find it, and practice and test yourself over and over until you can successfully find it every time. If you’re getting frustrated, it’s time to stop and have a sip of hot cocoa before you try again. This is supposed to be a fun treasure hunt, so make it enjoyable!

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Neptune’s Furnace

Sunday September 1, 2013

We’re going to do a chemistry experiment to simulate the heat generated by the internal core of Neptune by using a substance used for melting snow mixed with baking soda.

Calcium chloride splits into calcium ions and chloride ions when it is mixed with water, and energy is released in the form of heat. The energy released comes from the bond energy of the calcium chloride atoms, and is actually electromagnetic energy. When the calcium ions and chloride ions are floating around in the warm solution, they are free to interact with the rest of the ingredients added, like the sodium bicarbonate, to form carbon dioxide gas and sodium chloride (table salt).

Materials

Calcium chloride
Sodium bicarbonate (baking soda)
Phenol red or red food dye
Re-sealable plastic baggie
Gallon milk jug container
Straight pin
Warm water
Cold water

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Download Student Worksheet & Exercises

Cut the top off the milk jug just above the handle so you can easily put your experiment in the jug.
Fill your milk jug with cold water most of the way. Leave enough room for you to add the bag without overflowing the water, and make sure you put in very cold water. Set this aside.
Add an inch of warm water to the plastic bag.
Add a couple of drops of red dye to the bag.
If you are using a hot pack, open the hot pack (use scissors) carefully. You don’t want to puncture the water pouch inside. Throw the water pouch away and pour the rest of the contents into a container (this is calcium chloride). You want a couple of tablespoons of calcium chloride in the plastic baggie.
Seal the bag closed and roll the pellets between your fingers.
Use a straight pin and make six holes near the top of the bag, away from the water.
Open the bag and add a couple of tablespoons of sodium bicarbonate (baking soda). Quickly zip up your bag!
Make sure the bag is sealed before inserting it into your cold water jug. Watch carefully for several minutes and record your observations with the next step.
Draw your experiment during step 9. Label all parts of what’s going on with your experiment:

What’s Going On?

We’re simulating the heat generation on Neptune using a chemistry experiment with a hot pack.

Most instant hot packs available in drugstores work on this same principle we’re about to investigate. When the 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.

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

Dissolving calcium chloride is highly exothermic, meaning that it gives off a lot of heat when mixed with water (the water can reach up to 140^oF, so watch your hands!). The energy released comes from the bond energy of the calcium chloride atoms, and is actually electromagnetic energy.

When the calcium ions and chloride ions are floating around in the warm solution, they are free to interact with the rest of the ingredients added, like the sodium bicarbonate, to form carbon dioxide gas and sodium chloride (table salt). You can tell there’s carbon dioxide gas inside when the bag puffs up.

As the gas in the bag increases, it puffs out and increases the pressure. This stretches the bag and some of the gas is released out the holes in the top of the bag, bubbling up to the surface of the milk jug. After a while, the warm water will also rise out of the holes due to the temperature difference between the bag and jug and you’ll see red drift up to the top surface of the milk jug. The heat generated by Neptune is deep in the core, and it bubbles up and radiates out to space, just like the warm bag bubbling its contents to the cold water jug. The entire planet is a whirling, swirling, fast-moving ball of gas and ice that move because of temperature and pressure differences.

Neptune is one of the ice giants of our solar system, and the furthest planet from the sun. Because it’s a gas giant, you couldn’t land your spaceship on the surface because it doesn’t have one. You’d continuously fall until the pressure crushed your ship. And then when you got down far enough, you’d be roasted, because Neptune radiates 2.6 times more energy than it gets from the Sun. That’s impressive, especially since it’s so far from the Sun (30.1 AU, or more than 30 times the Earth-Sun distance). The average daily wind speed on Neptune is 1,200 mph. That’s four times faster than the biggest hurricanes on Earth!

Neptune has more mass than Uranus even though it’s smaller than Uranus. The rings around the planet weren’t confirmed until a space probe passed it and sent us back pictures of the blue planet. It’s hard for backyard astronomers to find this planet, since it’s not a naked-eye object. You need a complicated-looking set of star charts or a GPS tracking system coupled with astronomical data to point your scope in the right direction. Even then, all you see is a white-blue looking star.

Although it’s a gas giant, it’s classified as an ice giant, since there are large amounts of methane and ammonia ices in the upper atmosphere, giving the planet its blue color. The largest of 13 moons is Triton (not to be confused with Saturn’s massive moon, Titan), which orbits Neptune in the opposite direction from the planet’s rotation and also up at an incline from the planet’s equator.

Exercises

What happens when the chemicals come in contact with each other?
What did you notice when you sealed the bag closed and rolled the pellets between your fingers?
What happened when the solution is placed in the cold water jug?
What does this experiment have to do with Neptune? Why did we use the baking soda at all?

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Planetarium and Star Show

Sunday September 1, 2013

Greetings and welcome to the study of astronomy! This first lesson is simply to get you excited and interested in astronomy so you can decide what it is that you want to learn about astronomy later on.

We’re going to cover a lot in this presentation, including: the Sun, an average star, is the central and largest body in the solar system and is composed primarily of hydrogen and helium.

The solar system includes the Earth, Moon, Sun, seven other planets and their satellites (moons) and smaller objects such as asteroids and comets. The structure and composition of the universe can be learned from the study of stars and galaxies. Galaxies are clusters of billions of stars, and may have different shapes. The Sun is one of many stars in our own Milky Way galaxy. Stars may differ in size, temperature, and color.

Materials

Popcorn
Pencil

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Download Student Worksheet & Exercises

Before watching the video, print out your worksheet so you can jot things down as you listen. Then grab your pencil (and a handful of popcorn) and fill it in as you go along, or simply enjoy the show and fill it out at the end.

What’s Going On?

Astrophysics is the branch of astronomy that deals with the physics of the universe. Astronomers study celestial objects (things like stars, planets, moons, asteroids, comets, galaxies, and so forth) that exist outside Earth’s atmosphere. It’s the one field of study that combines the most science, engineering and technology areas in one fell swoop. Astronomy is also one of the oldest sciences on the planet.

Early astronomers tracked the movement of the stars so accurately that in most cases, we’ve only made minor adjustments to their data. Although Galileo wasn’t the first person to look through a telescope, he was the first to point it at the stars. Originally, astronomy was used for celestial navigation and was involved with the making of calendars, but nowadays it’s mostly classified in the field called astrophysics.

Questions to Answer:

What happened to Pluto?
How does the Sun make energy?
Which planet is your favorite and why?
How many moons around Jupiter and Saturn can you see with binoculars?
What’s the difference between a galaxy and a black hole?
How many Earths can fit inside the Sun?

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Song of the Sun

Sunday September 1, 2013

Helioseismology is the study of wave oscillations in the Sun. By studying the waves, scientists can tell what’s going on inside the Sun. It’s like studying earthquakes to learn what’s going on inside the earth. The Sun is filled with sound, and studying these sound waves is currently the only way scientists can tell what’s going on inside, since the light we see from the Sun is just from the upper surface.

Molecules are vibrating back and forth at fairly high rates of speed, creating waves. Energy moves from place to place by waves. Sound energy moves by longitudinal waves (the waves that are like a slinky). The molecules vibrate back and forth, crashing into the molecules next to them, causing them to vibrate, and so on and so forth. All sounds come from vibrations.

Materials

Musical instruments: triangles, glass bottles that can be blown across, metal forks, tuning forks, recorders, jaw harps, harmonicas, etc. Whatever you have will work fine.

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Download Student Worksheet & Exercises

Your teacher will pull out a bin of musical instruments of various types.
Assign one student to be the noisemaker. The rest will listen with their eyes closed and record their observations.
Everyone shuts their eyes except for the noise maker.
The noisemaker selects an instrument and plays it once. Everyone else listens.
The noisemaker selects another instrument and plays it once. Everyone listens.
The noisemaker selects a third instrument and plays it once. Everyone listens.
The noisemaker selects one of the three instruments and plays it as it moves. For example, if you’re playing the triangle, you can hit it and spin it. Or hit it as you are walking past the closed-eye listeners. Sound changes when the object is moving, so make the sound they hear appear to be different somehow.
The noisemaker puts the instruments back and everyone opens their eyes and records their data in the table.
Switch roles and find a new noisemaker for the next trial. Repeat steps 2-8.

What’s Going On?

The Sun is like the biggest musical instrument you’ve ever seen. A piano has 88 keys, which means you can play 88 different musical notes. The Sun has 10 million.

To play a guitar, you pluck one of the six strings. To play the piano, you hit a key and sound comes out. To play the flute, you blow across a hole. Drums require smacking things together. So how do you play the Sun?

Waves are the way energy moves from place to place. Sound moves from a mouth to an ear by waves. Light moves from a light bulb to a book page to your eyes by waves. Waves are everywhere. As you sit there reading this, you are surrounded by radio waves, television waves, cell phone waves, light waves, sound waves and more. (If you happen to be reading this in a boat or a bathtub, you’re surrounded by water waves as well.) There are waves everywhere!

Do you remember where all waves come from? Vibrating particles. Waves come from vibrating particles and are made up of vibrating particles.

Here’s rule one when it comes to waves….the waves move, the particles don’t. The wave moves from place to place. The wave carries the energy from place to place. The particles however, stay put. Here are a couple of examples to keep in mind.

If you’ve ever seen a crowd of people do the “wave” in the stands of a sporting event you may have noticed that the people only “vibrated” up and down. They did not move along the wave. The wave, however, moved through the stands.

Another example would be a duck floating on a wavy lake. The duck is moving up and down (vibrating) just like the water particles but he is not moving with the waves. The waves move, but the particles don’t. When I talk to you, the vibrating air molecules that made the sound in my mouth do not travel across the room into your ears. (Which is especially handy if I’ve just eaten an onion sandwich!) The energy from my mouth is moved, by waves, across the room.

Convection starts the waves moving. You’ve seen convection when a hot pot of water bubbles up. You can even hear it when it starts to boil if you listen carefully. Just below the surface of the Sun, the energy that started deep in the core has bubbled up to the surface to make gigantic bubbles emerge that are bigger than the state of Alaska. It’s also a noisy process, and the sound waves stay trapped beneath the surface, making waves appear on the surface of the Sun. This makes the Sun’s surface look like it’s moving up and down.

Scientists use special cameras to watch the surface of the Sun wiggle and move, and they look for patterns so they can determine what’s going on down inside the Sun. Since the sound is inside the Sun under the part we can see, we use sound to discover what’s inside the Sun.

Have you ever heard the Sun? The video is an actual recording of the song of the Sun.

If you’ve ever been inside an unfurnished room, you’ve heard echoes indoors. Sound bounces all around the room, just like it does inside the surface of the Sun.

Can sound waves travel through space? No. Sound requires a medium to travel through, since it travels by vibrating molecules, and there aren’t enough molecules in space to do this with (there are a couple random ones floating around here and there, but way too far apart to be useful for sound waves).

If you have a slinky, take it out and stretch it out to its full length on the table or the ground, asking someone to help you hold one end. Now move the slinky quickly to the left and back again, and watch the wave travel down the length and return. Now move your end quickly up and then back down the table, making a longitudinal wave. When this wave finishes, take your end and shove it quickly toward your helper, then pull back again to make a compression wave. Point out to the student how when the wave returns, it’s an echo. That’s what happens inside the Sun when the sound waves hit the surface of the Sun. They don’t go through the surface, but get trapped beneath it as they echo off the inside surface of the Sun.

Exercises

What did you notice that is different about the sounds you heard?
How can you tell that two sounds are different that came from the same instrument? (Movement causes sound waves to sound different.)
What did you notice about your guesses? What kind of instruments were you more correct about?

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Jupiter’s Jolts

Sunday September 1, 2013

Jupiter not only has the biggest lightning bolts we’ve ever detected, it also shocks its moons with a charge of 3 million amps every time they pass through certain hotspots. Some of these bolts are cause by the friction of fast-moving clouds. Today you get to make your own sparks and simulate Jupiter’s turbulent storms.

Electrons are too small for us to see with our eyes, but there are other ways to detect something’s going on. The proton has a positive charge, and the electron has a negative charge. Like charges repel and opposite charges attract.

Materials

Foam plate
Foam cup
Wool cloth or sweater
Plastic baggie
Aluminum pie pan
Aluminum foil
Film canister or M&M container
Nail (needs to be a little longer than the film canister)
Hot glue gun or tape
Water

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Download Student Worksheet & Exercises

Lay the aluminum pie pan in front of you, right-side up.
Glue the foam cup to the middle of the inside of the pan.
Lay the plate on the table, upside down. Place the pie pan (don’t glue it!) on top of the plate, back-to-back. Set aside.
Insert the nail through the middle of the film canister lid. Wrap the bottom of the film canister with aluminum foil. Tape the foil into place.
Fill the canister nearly full of water.
Snap on the lid, making sure that the nail touches the water.
Rub the foam plate with the wool for at least a minute to really charge it up. Place the plate upside down carefully on the table.
Put the pie pan back on top of the foam plate. The plate has taken on the charge from the foam plate.
Touch the pie pan with a finger… did you feel anything?
Use the cup as a handle and lift the pie pan up.
Touch the pan with your finger, and you should feel and see a spark (turn down the lights to make the room dark).
Charge the foam plate again and set the pie pan back on top to charge it up. (Make sure you’re lifting the pie pan only by the foam cup, or you’ll discharge it accidentally.)
Hold the film canister by the aluminum foil and touch the charged pie pan to the nail.
Rub the foam plate with the wool again to charge it up. Set the pie pan on the foam plate to charge the pan. Now lift the pie pan and touch the pan to the nail. Do this a couple of times to really get a good charge in the film canister.
Discharge the film canister by touching the foil with one finger and the nail with the other. Did you see a spark?
The wool gives the plate a negative charge. You can use a plastic bag instead of the wool to give the foam plate a positive charge.

What’s Going On?

If you rub a balloon on your head, the balloon becomes filled up with extra electrons, and now has a negative charge. Try the following experiment to create a temporary charge on a wall: Bring the balloon close to the wall until it sticks.

Opposite charges attract right? So, is the entire wall now an opposite charge from the balloon? No. In fact, the wall is not charged at all. It is neutral. So why did the balloon stick to it?

The balloon is negatively charged. It created a temporary positive charge when it got close to the wall. As the balloon gets closer to the wall, it repels the electrons in the wall. The negatively charged electrons in the wall are repelled from the negatively charged electrons in the balloon.

Since the electrons are repelled, what is left behind? Positive charges. The section of wall that has had its electrons repelled is now left positively charged. The negatively charged balloon will now “stick” to the positively charged wall. The wall is temporarily charged because once you move the balloon away, the electrons will go back to where they were and there will no longer be a charge on that part of the wall.

This is why plastic wrap, Styrofoam packing popcorn, and socks right out of the dryer stick to things. All those things have charges and can create temporary charges on things they get close to.

If you rub a balloon all over your hair, the Triboelectric Effect causes the electrons to move from your head to the balloon. But why don’t the electrons go from the balloon to your head? The direction of electron transfer has to do with the properties of the material itself. And the balloon-hair combination isn’t the only game in town.

Electrons move differently depending on the materials that are rubbed together. A balloon takes on a negative charge when rubbed on hair. Today, the kids are going to find when a foam plate is rubbed with wool, the plate takes on electrons and creates a negative charge on the plate. To give the plate a positive charge, kids can rub it with a plastic bag.

The Triboelectric Series is a list that ranks different materials according to how they lose or gain electrons. A rubber rod rubbed with wool produces a negative charge on the rod, however an acrylic rod rubbed with silk creates a positive charge on the rod. A foam plate often has a positive charge when you slide one off the stack, but if you rub it with wool it will build up a negative charge.

Near the top of the list are materials that take on a positive charge, such as air, human skin, glass, rabbit fur, human hair, wool, silk, and aluminum. Near the bottom of the list are materials that take on a negative charge, such as amber, rubber balloons, copper, brass, gold, cellophane tape, Teflon, and silicone rubber. Scientists developed this list by doing a series of experiments, very similar to the ones we’re about to do.

Exercises

What happens if you hold the nail and charge the aluminum foil?
Can you see electrons? Why or why not?

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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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Exercises for Geology

Sunday September 1, 2013

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What is the definition of a rock?
What does it mean if there’s no streak left on the streak plate?
Give an example of a kind of rock that leaves a streak a different color than its surface color.
If a mineral scratches a penny but doesn’t get scratched by a nail, can you approximate its hardness?
Give examples of the hardest and softest minerals on the Mohs’ Scale of Hardness.
Name three properties geologists look for when they try to categorize a mineral.
If you break a sample of quartz and find that it has no clean surfaces of separation, what kind of cleavage does it show?
What are two things we use coal for?
What is the equation for finding density?
10. How is fluorescence different from phosphorescence?
Is lodestone the same as magnetite?
Name three characteristics of pumice.
What is a crystal, and how is it different from a mineral and a rock?

Need answers?
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Exercises for Atmosphere

Sunday September 1, 2013

Let’s see how much you’ve picked up with these experiments and the reading – answer as best as you can. (No peeking at the answers until you’re done!) Just relax and see what jumps to mind when you read the question. You can also print these out and jot down your answers in your science notebook.
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1. How does radiation travel?
a. As a beam
b. As a wave
c. as a molecule

2. Where does most of the energy on earth come from?
a. Underground
b. The Sun
c. The Oceans

3. What is one way that we use energy from the sun?

4. Which instrument measures humidity?
a. Thermometer
b. Barometer
c. Hygrometer
d. Rain Gauge

5. What is the unit of measurement for temperature here in the USA?
a. Newtons
b. Joules
c. Fahrenheit
d. Celsius

6. What is another unit of measurement used for temperature?
a. Fahrenheit
b. Celsius
c. Joules
d. Newtons

7. What is the science called that investigates the weather and patterns of the Earth’s atmosphere?
a. Zoology
b. Biology
c. Meteorology
d. Nephology

8. What are clouds made of?
a. Nitrogen
b. Water
c. Oxygen
d. Iridium

9. What form of water exists in clouds
a. Water vapor
b. Liquid water
c. Frozen water

10. What is the name of someone who studies the weather?
a. Oncologist
b. Herpetologist
c. Climatologist
d. Meteorologist
e. Asteroidologist

11. What is the type of energy that comes from the sun?
a. Potential
b. Kinetic
c. Electronic
d. Radiation

12. What principle describes how pressure behaves in a moving fluid?
a. Avogadro’s Principle
b. Bernoulli’s Principle
c. Boyle’s Law
d. Pascal’s Wager

13. A higher pressure will ________ an object.

14. An object experiences pressure in the Earth’s atmosphere in which direction more?
a. Upwards
b. Downwards
c. Equally in all directions

15. If an object is higher in altitude above the earth, it experiences which pressure in relationship to an object at sea level?
a. Greater Pressure
b. Less Pressure
c. Equal Pressure

Need answers?
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Answers to Exercises

Sunday September 1, 2013

Let’s see how you did! If you didn’t get a few of these, don’t let it stress you out – it just means you need to play with more experiments in this area. We’re all works in progress, and we have our entire lifetime to puzzle together the mysteries of the universe!

Here’s printer-friendly versions of the exercises and answers for you to print out: Simply click here.
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Answers:

How does radiation travel? (as a wave)
Where does most of the energy on earth come from? (the Sun)
What is one way that we use energy from the sun? (appropriate energy answer)
Which instrument measures humidity? (Hygrometer)
What is the unit of measurement for temperature here in the USA? (Fahrenheit)
What is another unit of measurement used for temperature? (Celsius)
What is the science called that investigates the weather and patterns of the Earth’s atmosphere? (Meteorology)
What are clouds made of? (Water)
What form of water exists in clouds (Water vapor)
What is the name of someone who studies the weather? (Meteorologist)
What is the type of energy that comes from the sun? (Radiation)
What principle describes how pressure behaves in a moving fluid? (Bernoulli’s principle)
A higher pressure will ________ an object. (Push on)
An object experiences pressure in the Earth’s atmosphere in which direction more? (Equally in all directions)
If an object is higher in altitude above the earth, it experiences which pressure in relationship to an object at sea level? (Less pressure)

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Answers to Exercises

Sunday September 1, 2013

What is the definition of a rock? (Something that is made of two or more minerals.)
What does it mean if there’s no streak left on the streak plate? (The mineral is harder than the streak plate, which means it has a hardness of above 7.)
Give an example of a kind of rock that leaves a streak a different color than its surface color. (Pyrite is gold, but its streak is green-black.)
If a mineral scratches a penny but doesn’t get scratched by a nail, can you approximate its hardness? (Over 5.5)
Give examples of the hardest and softest minerals on the Mohs’ Scale. (Diamond = 10, Talc = 1)
Name three properties geologists look for when they try to categorize a mineral. (Color, hardness, fluorescence, magnetism, luster, how they break, if they react to acid, etc.)
If you break a sample of quartz and find that it has no clean surfaces of separation, what kind of cleavage does it show? (none)
What are two things we use coal for? (heating water and generating electricity)
What is the equation for finding density? (density = m/V)
How is fluorescence different from phosphorescence? (Minerals that are fluorescent glow when exposed to a UV light. Minerals that continue to emit light even after the UV light has been switched off are phosphorescent.)
Is lodestone the same as magnetite? (Lodestone is the magnetic version of magnetite.)
Name three characteristics of pumice. (light-colored, floats on water, and is porous.)
What is a crystal, and how is it different from a mineral and a rock? (Crystals are a structure of a regular pattern of atoms within a solid. A mineral is an inorganic substance. All minerals are crystalline. Rocks are composed of two or more minerals. Not all crystals are minerals.)

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Giant Crystals

Saturday August 31, 2013

The Cave of Crystals in Mexico has the world’s largest selenite (gypsum) crystals about 1,000 feet below the surface in a hot cavern. Some of the crystals are over 50 tons in weight and 35 feet in length!
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Scientists that study these crystals have to wear special suits filled with ice packs along with respirators so they can stay cool and comfortable, since the air is thick with water 99% humidity and temperatures from 110-136 degrees Fahrenheit. Without these special suits, people would last only ten minutes, which means that most of the cave is still largely unexplored.

If you’re interested in these caves, look up information on the Naica Project to learn more.

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Rock Hound Workshop

Saturday August 31, 2013

Today you get to sort and identify as many rocks as you can as you test for streak, hardness, fluorescence, color, magnetism, chemical reactions, and more with this unique set of rocks. You may have to do a little research on the ones that are not yet familiar to you!

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Materials:

“Washington Student Rock Pack” (see list below for samples that are included)
Penny
Nail
Streak plate
Water in a graduated container
Scale that measures in grams
Longwave UV light source

Download worksheet and exercises

NEW! I’ve improved the worksheet, so you can download the latest edition here.

You’re first going to classify your pile of rocks right along with the instructional step–by-step video. So fire up the video and get your materials out as you complete the data table.
You’ll be testing for color, streak, hardness, density, luster, cleavage, fracture, tenacity, acid reaction, and fluorescence. Enjoy your third real geologist rock hunt!
Here are the minerals and rocks included with this set:

Calcite
Calcareous Tufa
Pyroxene
Limestone
Gypsum
Conglomerate
Amphibole
Fossiliferous Limestone
Quartz
Sandstone
Mica – Muscovite
Shale
Feldspar – Microcline
Bituminous Coal
Feldspar – Plagioclase

Clay
Bauxite – Aluminum Ore
Porphyry
Limonite – Iron Ore
Obsidian (or Pitchstone)
Hematite – Iron Ore
Felsite
Pyrolusite – Manganese Ore
Pumice
Magnetite – Iron Ore
Basalt
Copper Ore

Gabbro
Pyrite – Iron-Sulfur Ore
Granite
Fluorite
Slate
Sulfur
Gneiss
Barite
Marble
Graphite
Mica Schist
Talc
Quartzite

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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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Telling Time by the Stars

Tuesday June 25, 2013

The stars rise and set just like our sun, and for people in the northern hemisphere, the Big Dipper circles the north star Polaris once every 24 hours. Would you like to learn how to tell time by the stars?

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From the northern hemisphere, the Big Dipper is above the horizon for most of the year. In the spring time (especially in March), it’s fun and easy to learn how to tell time by the stars!

First, go outside after sunset and find the Big Dipper. Use a compass if you need to to find NORTH, then tilt your head back and look up from the horizon for seven bright stars.

Draw a line through two bowl stars (furthest from the handle) and extend that line so it hits the north “pole” star Polaris.

The “sky clock” is a 24-hour clock, not a 12-our clock like the one in your house. Polaris is the center of the clock, and the hour hand is the line you drew from the Big Dipper to Polaris.

Now use this simple formula: The current TIME = the clock reading MINUS twice the number of months after March 6. (You can use March 1 to make it easier to figure out.) Imagine we’re in March right now, so that “number of months past March” is ZERO. (See why it’s easy in March?) So go look up at the sky clock and read what time it is!

Notice how we read the sky clock COUNTERCLOCKWISE. This is opposite of the clock in your kitchen.

Let’s take another example. Suppose it’s Dec. 1st.

Dec 1 is close to Dec 6, so let’s figure about 9 months (to be exact, it would be 8.75 months, but let’s make it easy to calculate this time through). The night sky looks like the second image (without the clock superimposed over it). Can you tell me what time it is?

ANSWER:
The clock reads 2PM. The correction is 2 x 9 = 18. That is 18 hours we will need to SUBTRACT from 2PM.

So the time I read on the clock is about 2am (you could say 1:30am, but I am trying to make it easier here).

Now subtract 12 hours to make that PM into AM.

Now we only need to subtract 6 more hours.

Subtract 6 hours from 2AM to get 8PM!

The more you practice this, the easier it will be!
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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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Does it rain on the sun?

Saturday March 2, 2013

Does it rain on the Sun? The answer to this is yes, however, it is not water that falls but very hot plasma. On July 19, 2012, there was an eruption on the Sun that produced a massive burst of solar wind and magnetic fields and released into Space. This eruption also produced a powerful solar flare. After that, a phenomenon known as coronal rain occurred. Corona Rain occurs occurs when hot plasma in the corona cools and condenses in strong magnetic fields, usually associated with regions that produce solar flares. The plasma condenses and slowly falls back to the solar surface.

The electrons, protons and ions in the rain is forced to move along the magnetic loops of the Sun’s surface. As a result, this bright flare highlights matter glowing at a temperature of about 50,000 Kelvin. The entire coronal rain lasted about 10 hours.

Video Credit : http://apod.nasa.gov/apod/ap130226.html

Positive and Negative Integers

Friday December 7, 2012

Numbers that are not fractions or decimals, are called integers. Numbers like: 2 and 144 and 299,792,458 (that’s the speed of light in meters per second) are all integers!

Integers can be positive or negative. If the number is greater than zero, like 4, 16, 25… then it’s a positive integer. Negative integers are -15, -42, -1 million.

It’s important to know how to handle both positive and negative integers because they come up all the time in algebra. You probably already have experience in working with positive and negative decimals and fractions, so now let’s do a quick review so you can make sure you’ve mastered the basics.
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Ham Radio Essentials

Saturday September 1, 2012

“CQ, CQ.. calling CQ 20 meters. This is KJ6ZFH calling. Kilo Juliet Six Zulu Foxtrot Hotel in San Luis Obispo calling CQ 20 meters. Hello CQ, CQ, CQ 20 meters. This is KJ6ZFH calling. Kilo Juliet Six Zulu Foxtrot Hotel in San Luis Obispo calling CQ 20 meters and standing by for a call.”

What is all THAT?

Well, it’s a “ham” radio operator calling out to anyone listening on a special radio frequency (the 20 meter band) inviting them to answer and talk. It’s a fun and exciting hobby for those who love electronics and meeting new people from all over the world. Plus it’s an ideal hobby for students because it’s inexpensive (there’s no on-going cost once you’ve bought your radio, unlike a cell phone plan), provides a huge amount of learning opportunities from geography to electronics to foreign language, and it’s just plain cool.

Amateur radio has been around for a long time (since 1912), so you never know who you’re going to make contact with when you put out a call. A friend of mine actually talked with the King of Jordan once… no kidding!

You can even connect with astronaut hams on the International Space Station (see the image on the left… notice her hair?) Suni Williams is using the space station’s radio module to communicate with kids on earth. There’s really no limit to what you can do once you learn the fundamentals.

I’m going to outline the basics of amateur radio so you can really get a feel for what it is, why people still love it, and what it’s really like out there in the air. Let’s start with the first thing people always ask me, which is: “What is CQ?” “CQ” means “calling any station”. Calling “CQ” takes about 20-30 seconds to say clearly, and includes the call sign (KJ6ZFH) several times, including phonetically (Kilo Juliet Six Zulu Foxtrot Hotel). Also includes the location information so the listener knows exactly who and where the caller is.

The videos on this page were created by Tyler, and his call sign is N7TFP. He’s extremely passionate about amateur radio, and he has created several videos on the hobby that I thought you might enjoy, including a peek at his radio shack. The “shack” refers to the place you do your “hamming”, usually in a shed or room where all your radio equipment is located. Some hams operate from their homes, others wire up their vehicles with portable radio stations, some hams set up a separate building in the yard, and a few had to be sneaky about hamming, especially if their housing development or family didn’t approve of their rooftop antennas. In fact, I know of one ham that was so desperate to continue his hobby, despite his wife’s objections that he stashed his radio equipment in a tiny closet and figured out a way to use the metal rain gutters as his antenna!

Let’s take a look at how a ham operator works:

If you’ve got your Amateur Radio License (we’ll talk more on how to do that later), you are ready to get on the air! First thing you should do is listen to how other hams do their communication so you can pick up on a few things. Different bands have different approaches to communication, so it really helps to hear a couple of exchanges before you make your first contact. Most people start with a Technician license with either a handi-talkie (hand-held transceiver) or a portable radio by going through something called a local “repeater”. Let me explain: The most popular way to communicate for a newly licensed ham to talk with other hams is through a local repeater. It’s a two-way radio system that receives communication on one frequency and then re-transmits what it hears on another frequency at exactly the same time. It’s simply a machine that relays your message since your transceiver has a limited range. It’s limited because of the size of the antenna and how the earth curves. A repeater can get your signal to reach a much further listener this way. There are repeaters all over the country. To make a contact on the 2 meter band through a repeater, I press the mike button and say:

- “KJ6ZFH listening.” (Make sure you use your own call sign!). Now this may be all I need to do in order to get a response. But more often than not, there’s no response at all. So then I try again but add in a little more information like this:

“KJ6ZFH is monitoring and listening for a call.” Usually I don’t need to call CQ on a repeater, although there’s nothing in the rule books that say you can’t do that. I’ll tell you more about calling CQ in a moment.

When you get a response, it might sound something like this:

“KJ6ZFH this is W2AYL in St. George returning. My name is Pat. Back to you. W2AYL”. Then I’d wait for the repeater’s tone for the go-ahead to proceed with communication.

I’d press my mike button and respond, because now I’m in! Sometimes I give my name and location or any other info I want to talk to Pat about.

When I’m done talking, I say: “Over” or “Back to you.” I also make sure to give my call sign frequently (you’re required to do this every 10 minutes minimum). An easy way to do this is to tack it on at the end: “W2AYL this is KJ6ZFH. Over.”

When I’m done talking with Pat but still want to continue to monitor, I say goodbye by saying 73 (which means ‘best wishes’) and sign off like this: “W2AYL 73, this is KJ6ZFH clear and monitoring.”

If I’m done for the night, I would say: “W2AYL 73, this is KJ6ZFH clear and QRT” instead.

And that’s it! It’s really that simple. And it exciting and fun to keep track of all the different folks you get to talk with all over the country and world.

Make Contact by Calling CQ

“CQ” means “calling any station”. Some licenses permit you to operate on different bands, like SSB on 10 meters. Here’s what you’d do in this case: You always start by finding a clear frequency. Let’s say you’ve chosen to operate on 28.460. You want to speak clearly and ask “Is this frequency in use? This is KJ6ZFH.” If you don’t get a response, ask a second time just to be sure. If there’s still no response, you can continue. However, note that if the frequency is in use, just move to another frequency and try again.

Now you get to call: “CQ CQ CQ. This is Kilo Juliet Six Zulu Foxtrot Hotel calling CQ CQ CQ. This is Kilo Juliet Six Zulu Foxtrot Hotel, KJ6ZFH calling CQ and waiting for a call.” Wait and listen for a return call. If you’re on an HF (high frequency) band like 10 meters, the signal you get back might be very strong to very weak or anything in between, so use your ears here.

You may hear “Kilo Juliet Six Zulu Foxtrot Hotel this is (their call sign) calling.” You respond by saying “(Their call sign, using phonetics) this is KJ6ZFH. Thanks for the call your signal is 59. My name is Aurora and my QTH is San Luis Obispo. So how do you copy? (Their call sign) this is KJ6ZFH over.”

You made HF (high frequency) contact! You can make the contact as you wish depending on the band conditions and what you find to discuss with your new friend in a new country!

Q Signals

Q signals are used primarily in CW. They provide an abbreviated way of asking a question or making a statement. A Q signal followed by a question mark (?) asks a question. A Q signal without the “?” answers the question or makes the statement.

The following are Q signals commonly used by CW operators world wide:

- QSY – Shall I change to to transmission on another frequency? Change transmission to another frequency (or ___ kHz).

QTH – What is your location? My location is ___.

QRZ – Who is calling me? You are being called by ___ (on ___ kHz).

QSL – Can you acknowledge receipt? I am acknowledging receipt.

QSO – Can you communicate with ___ direct or by relay? I can communicate with ___ direct (or by relay through ___).

QRP – Shall I decrease power? Decrease power.

QRM – Is my transmission being interferred with? Your transmission is being interferred with ___. (1. Nil 2. Slightly 3. Moderately 4. Severely 5. Extremely)

QRN – Are you troubled by static? I am troubled by static —. (1-5 as under QRM)

You can find a complete list of Q signals here.

Building Your Amateur Radio Station

If you’re ready to build your own amateur radio station, here’s a video to get you started:

Your First Radio

This is a video on selecting your first radio. Some folks feel that a HT (handi-talkie, or hand-held transceivers) does not make good first radios, however for kids it’s a great first step into the hobby, and it’s not a huge investment… and it comes with the antenna and everything you need, all in one package. You can get a Baofang UV-5R if you’d like an inexpensive handi-talkie for about $60.

If you’d like a larger radio, get yourself a portable radio 30-60W in the 2 meter / 70cm bands – this will keep you busy for a long time. My first radio was the Yaseu 7900.

Sometimes, you’ll hear reference to the word “oscilloscope” or “o-scope”. If you’re wondering what it is, it an instrument used in the electronics/electrical fields (which includes radio) to help hams keep their equipment working properly. Most folks get their first exposure to one of these in a college level lab, but here’s sneak peek so you don’t have to wait. Here’s how it works:

The first thing you’ll want to do is set up your radio to the appropriate frequency, offset, CTCSS tone (if needed) so you’ll be ready to make your contact – all of this is covered in your instruction manual that comes with your radio.

Silly as this sounds, I spent to much time getting my equipment dialed in right that when it came time to speak, I clean forgot my call sign! I had to stick it (KJ6ZFH) on a post-it note right in front of me so I wouldn’t forget.

Getting Your Amateur Radio License

After watching these videos and learning about radio communication, are you ready to get your license? If you’re excited about the idea, then NOW is a great time to jump on it. Would it surprise you to know that when I got my license, I woke up the morning of the test without even knowing that I was about to take the test? Not only that, I had not even cracked open an book on the subject? Sure, there are only 35 questions to answer, and they take them from a published pool of 350 questions, but honestly, it was a surprise date from my husband.

He drove me to a testing center where we studied for 5 hours, then took the test… all in a single day! No long weeks of studying theory, no late nights or giving up other activities… just a day of studying, take the test, and boom! I got my license. It cost me $20. So I totally encourage you to do it now while you’re excited and have momentum in this direction… that’s the moment you make the decision that takes you in a direction you really want to go. You can look up information on testing at the ARRL.

Enough said – here’s a quick video on getting your license you might find helpful:

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

Curiosity Rover Successfully Lands on Mars on August 5th!

Tuesday August 7, 2012

This is the stuff of dreams, imagination, creativity and innovation.This is especially cool for parents to have their children witness something “out of this world” live as it happens. This is American science education at its absolute finest.

NASA’s Jet Propulsion Laboratory (JPL) has done it again, BIG TIME!

In normal fashion for JPL in Pasadena, this was no normal, everyday kind of landing, as Curiosity will blast into the Martian atmosphere at 13,000 miles per hour and in a death-defying “Seven Minutes of Terror” come to a soft landing on Mars. Fingers and toes were crossed. And, due to its heavy weight, it will not land like Spirit and Opportunity did about 8 years ago landing in cushioned, inflated air bags that looks like giant raspberries. Curiosity was lowered to the surface under a rocket-powered sky-crane, never before attempted by any spacecraft. Mars Science Laboratory Curiosity is the most sophisticated and complex robotic spacecraft ever built.

Even now that this event has happened, you can witness this history-making event through these special NASA TV video along with millions of people around the world.

Curiosity was launched on an Atlas V rocket from Cape Canaveral on November 26, 2011:

Some folks may have heard that there was a problem anticipated with the transmission of the landing telemetry (radio signal), possibly taking hours before we would know what happened during the landing. That problem was with America’s Mars Odyssey spacecraft orbiting Mars (along with America’s Mars Reconnaissance Orbiter and Europe’s Mars Express Orbiter). A “reaction wheel” that helps control Mars Odyssey’s orbital path location had problems, that could have impacted its ability to receive and relay the telemetry as it happens. The week before landing, JPL engineers successfully corrected the issue, putting Mars Odyssey back on course to directly receive the landing telemetry and beam it back to Earth as it is happening.

Newsflash! Curiosity has successfully landed on the surface of Mars!

Bear in mind that the transmission time from Mars to Earth will be about 14 minutes at the speed of light, so Curiosity will have experienced the Seven Minutes of Terror and landed before we get the signals from Mars. Hold your breath and wish Curiosity the best as you watch these videos!

Here are some of the first images:

More images are being posted by NASA here: Mars Science Laboratory Image Gallery

What is Math?

Tuesday July 31, 2012

What is math? It can be compared to a very useful tool, or maybe a collection of tools. Sometimes textbooks concentrate a lot on teaching about the small details of each and every type of tool. But it’s also really important to focus on how and when to use the different tools. This is my practical approach to teaching the subject. And it’s also important to note that math is much more than just numbers! If you’re really good with shapes and how they relate, you might enjoy geometry. And if you are good at solving puzzles, chances are that logic will be a great match for your skills.

NOTE: Be sure to pause the video when the timer reaches 6:30 to work on the Earn, Break Even, or Lose problem.

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Which did you like best – the Earn, Break Even, or Lose question, the circle drawing trick or the Bagels game? This might help you discover if you’re more interested in numerical problems, geometry, or logic. Try all of these with a friend. Which one do they prefer?

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How to Multiply by 12

Tuesday July 31, 2012

Do you think you'll need to know how to multiply by 12 or 11 more? Think of it this way: how often do you need to figure out how many dozen you need of something? It comes up a lot more than needing to know how many batches of 11, doesn't it? That's because of the way we've decided to group things mathematically as a society.

Here's why: We picked 12 based on how we used to count on our fingers using the "finger segment" system. If you look at your hands, you'll notice that your index finger has three segments to it. So does your middle finger, ring finger, and pinkie. Since you have four fingers, you actually have 12 sections for counting with (we're not including your thumb, which is the pointer... your thumb rests on the section you're currently on). When your thumb touches the tip of your index finger, that means "1". When your thumb touches the middle segment, that's "2", and the base segment is "3". The tip of your middle finger is "4", and so on. That's how we came to use the 12-in-a-batch system.

If you're wondering why we didn't use the 24-in-a-batch system (because you have two hands), that's because one hand was for 1-12 and the second hand indicated the number of batches of 12. So if your left hand has your thumb on the ring finger's base segment (9) and your right hand has the thumb touching the index finger's middle segment (2 complete batches of 12, or 2 x 12), the number you counted to is: 24 + 9 = 33.

Fortunately we now have calculators and a base-ten system, so this whole thing worked out well. But still the number 12 persists! So I thought you'd like this video, which expands on the idea of quickly multiplying two-digit numbers and three-digit numbers by eleven. This is very similar to the shortcut used when multiplying by eleven, but it also involves some doubling. Are you ready?

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Download Student Worksheet & Exercises

Isn’t this a really cool (and FAST) way to multiply by twelve? It's a lot faster than using the Babylonian finger-segment system. Try some problems on your own and check your work with a calculator.

How do you think this works?

Exercises

11 x 543
12 x 45
12 x 326
12 x 769
12 x 1345
12 x 3461
12 x 7532
12 x 8989
12 x 9999
12 x 98749

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Divisibility

Tuesday July 31, 2012

Can you look at a number and tell right away if it’s divisible by another number? Well, it’s pretty easy for 2 – if it’s an even number, it’s definitely divisible by two. Testing whether a number is divisible by five is easy as well. How can you tell?

In this video, I’ll show you some tricks to determine if a number is divisible by 3, 4, 6 and 7 before you start to divide. Some are simple and fast and some are a bit more complex. These can be very useful tricks for working with larger numbers (or just really fun to play with for a bit).

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Download Student Worksheet & Exercises

It’s pretty complex to be able to tell if a number is divisible by 7, but I think it's really neat that there’s a way to figure it out before you actually do the math. What do you think?

Exercises

Identify the number(s) that are divisible by 2 in the following list.
301, 3645, 3673
Identify the numbers that are divisible by 3 in the following list.
3981, 430, 4598, 72624
Which one of the following numbers is divisible by 7
5894, 56723, 17259
Is 2353740 divisible by 4?
Which one of the following numbers is divisible by both 2 and 5?10002, 453970, 637385
A number is divisible of 2 and 3, will it be divisible by 5?
If a number is divisible by 2 only, will it be divisible by 4?
Which of the following numbers is divisible by 3?
45769, 25784, 2391
List any three 3-digit numbers that are divisible by 5.
List two 4-digit numbers that are divisible by 4.

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What Day Were You Born On?

Tuesday July 31, 2012

This is not only a neat trick but a very practical skill - you can figure out the day of the week of anyone's birthday.

If you were born in the 20^th Century, (1900-1999), we can use math to find out which day of the week you were born. If you’re a little too young for this, try it with a parent or grandparent’s birthday. Watch the video and I'll teach you exactly how it works.

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Download Student Worksheet & Exercises

Did it work? You can check via the Time and Date website, or simply do an internet search for the year and the word calendar, such as, “1996 calendar.”

Note: the codes shown in the video are special just to the years in the 1900s. If you'd like to be able to expand this to other centuries, you'll need to use the codes listed below and learn how to shift them (like I did for you in the video).

What about years 2000-2099?

The general formula is: Month Code + Date + Year Code - (biggest multiple of seven).

For Nov. 18, 2006 = 2 + 18 + 0 = 20.

20 - (7 * 2) = 20 / 14 = 6 so Nov 18, 2006 is on a Saturday using the codes below! (Do you notice how the following codes are different than they were for 1900s?)

Day Codes:

Sunday = 0
Monday = 1
Tuesday = 2
Wednesday = 3
Thursday = 4
Friday = 5
Saturday = 6
Sunday = 0 or 7

Month Codes:

January = 6*
February = 2*
March = 2
April = 5
May = 0
June = 3
July = 5
August = 1
September = 4
October = 6
November = 2
December = 4

*For leap years (2000, 20004, 2008, 2012, 2016...) the code for Jan = 5 and Feb = 1.

Year codes:

2000 = 0
2001 = 1
2002 = 2
2003 = 3
2004 = 5
2005 = 6
2006 = 0
2007 = 1
2008 = 3
2009 = 4
2010 = 5
2011 = 6
2012 = 1
2013 = 2
2014 = 3
2015 = 4
2016 = 6
2017 = 0
2018 = 1
2019 = 2
2020 = 4
2021 = 5
2022 = 6
2023 = 0
2024 = 2
2025 = 3

We don't have to memorize 2000-2099 because we know how to divide numbers since the table repeats itself.

Here's how it works: if you need the code for 2061, divide 61 by 4 to get 15 (with a remainder of 1 that we ignore), so 2061 has a year code of 61 + 15 = 76. Don't forget to subtract out any multiple of 7, so we get 76 - 70 = 6. The year code for 2061 is 6!

This works the same way for the 1900s: Fir December 3, 1998 we have 98 divided by 4 which gives 24 (with a remainder of 2 that we ignore), so 1998 has a year code of 98 + 24 + 1 = 123. Now subtract out the biggest multiple of seven (which is 119) to get 123 - 119 = 4. 1998 has a year code of 4!

What about year codes for other centuries?

Did you notice how I added "1" to the year code in the previous example? That's because I had to shift it over since it's in the 1900s. For the 1800s we'd shift it by 3. Let me show you how:

Abraham Lincoln's birthday is Feb 12, 1809. 2009 has a year code of 4, that we need to add 3 to (this is the shift by 3), so we get 7 (which reduces down to zero). The year code for 1809 is 0.

So, his birthday is: 2 + 12 + 0 - 14 - (biggest multiple of seven) = 14 - 14 = 0.

Lincoln was born on a Sunday!

For 2100 dates, you'd need to add 5 to the year code (or subtract 2 from the year code). For example, 2109 has a year code of 4 + 5 = 9. Subtract out 7 gives a year code of 2. For 1700s, you'll treat them just like the 2100s.

Why does this work?

We're using a Gregorian calendar. While this type of calendar was created in 1580s, it wasn't until Wed, Sept 2, 1752 when it was adopted by England and American colonies. 1752 has a year code of zero. Which is why this method won't work for any dates before this, as they were on the Julian calendar. Note that the Gregorian calendar repeats itself every 400 years, so you can convert any future date into a date near 2000. For example, March 19, 2361 and March 19, 2761 will both be on a Sunday.

Exercises

Identify the days corresponding to the following dates given in the format,: mm/dd/yyyy

11/16/1997
1/1/1997
05/27/1995
08/15/1997
07/15/1977
03/01/1977
11/24/1974
06/27/1958
In a certain family, Janet was born on May 20, 1992 while Lewis was born on March 31, 1996. Who was born on Sunday?
On which day is April 30, 1960?

[/am4show]

Paperclip Trick

Tuesday July 31, 2012

For this puzzle, you’ll use three cups and eleven objects. The first challenge is to put an odd number of objects in each cup. Is this pretty simple? How many different combinations can you come up with for the eleven objects?

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Download Student Worksheet & Exercises

Now how about if we take an object away and use ten instead? Is this puzzle more challenging? Here’s a hint: can you figure out a way for an object to be in two different cups at the same time? Work on this for a little while prior to watching the solution.

Pretty cool, right? I hope you enjoyed this trick. Mathematics and paradoxes can really be a lot of fun!

Exercises

What is an even number?
What is an odd number?

If you have 8 paperclips and three cups, arrange the paperclips you that you have an odd number in each cup. Find three different solutions (arrangements) to solve this problem.

First arrangement
Second arrangement
Third arrangement

Now you have 11 paperclips and three cups. Find two new solutions (ones we haven’t covered yet in this lesson) to having an odd number in each cup.

First arrangement
Second arrangement

Reduce your number to 10 paperclips. Find four new solutions (ones we haven’t covered yet in this lesson) to having an odd number in each cup. (Is it easier this time?)

First arrangement
Second arrangement
Third arrangement
Fourth arrangement

[/am4show]

New Year’s Puzzle

Tuesday July 31, 2012

This is a really fun riddle! It’s a math logic puzzle involving the calendar that will really blow your mind. Pay close attention to the clues I give in the video and see if you can work out how it works. Pause the video at about the 1:30 mark if you would like to try and work out the answer before I show you how it works!

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Download Student Worksheet & Exercises

What do you think about this riddle? It’s a fun puzzle and it shows you how to effectively use a timeline in order to solve a logic problem involving the calendar. Pretty cool, right? Sometimes drawing a diagram can help you to work out details of a puzzle by giving you a visual aid to reference.

Exercises

Your exercise for this lesson is to not only challenge someone else with this problem, but be able to explain it to them in a way that they understand the solution. Go for it!

[/am4show]

Logic Numbers

Tuesday July 31, 2012

This is a neat logic trick which allows you to flip over a stack of cards numbered 1-10. When you flip the back upright, they are in numerical order. There is a special way to make it work, so pay close attention to the video. I’ll show you exactly how it works.

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Does this make sense? What order do you think the cards need to go in so that the trick works? Use your logic skills to work it out.

Exercises

Your exercise for this lesson is to not only challenge someone else with this problem, but be able to explain it to them in a way that they understand the solution.

[/am4show]

Hex

Tuesday July 31, 2012

Hex is a super fun game! It starts with a grid of hexagons (six-sided shapes) and two players. You can color in any cell on your turn. The ultimate goal is to be the first one to complete a chain across to the other side of the board.

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Here’s a link to the game board for you to print and use.

Using the pie rule can help with the advantage that the first player gets. This means the second player can choose to switch positions with the first player after they’ve made their first move. Can you use your logic skills to find strategies that make getting across the board easier?
[/am4show]

Magic Squares

Tuesday July 31, 2012

Magic squares have been traced through history as known to Chinese mathematicians, Arab mathematicians, India and Egypt cultures. The first magic squares Magic squares have fascinated people for centuries, and historians have found them engraved in stone or metal and worn as necklaces. Early cultures believed that by wearing magic squares, it would ensure they had long life and kept them from getting sick.

Benjamin Franklin was well-known for creating and enjoying magic squares, and it was all the rage during his time. Here's the deal: we're going to arrange numbers in a way so that all the rows, columns, and even the diagonals add up to a single number (called a Magic Sum). In this video, I show you the first Magic Square published in Europe way back in 1514. Plus, I show you how to make your very own Magic Square. You can use it to test your friends.

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You can create a magic square that sums to any number by referencing the original "34" magic square. Ask a friend for a number larger than 34 (which is the smallest magic square you can create), and then follow these easy steps:

1. First take the number your friend gave you and subtract 34.
2. Divide your number from #1 by 4 and keep the remainder to use like this: the quotient is the first magic number and the quotient plus the remainder is the second magic number. For 67 the results are 8 and 9.
3. When you fill out a square in your new 4x4 magic square, peek at the 34-magic-square and see what's already in the box. If it's a 13, 14, 15, or 16, then add the second number to it and put it int he box. If not, add the first number to it.

Note that if your number is even (but not a multiple of 4) then you'll have the same number for your first and second numbers. That's okay!

Exercise

Find the value of the letters; A, B,C and D in the following upside-down magic square

18	A		61
D	81	98
91	B		88
C	68		96

A
B
C
D
What is the sum of elements of any diagonal in the first magical square published in 1514?
Find the element at the middle of a nine-element magic square.
Draw a nine-element magic square.

Find the values of b and c in the following magic square.

16		2
c	10	11	8
	6	7
		d	b

[/am4show]

Bagels

Tuesday July 31, 2012

If you’ve watched my “What Is Math?” video, you’ve seen a sample of the Bagels math logic game. This is one of my family’s favorites! It’s a guessing game, but you can use logic and strategy in order to guess the numbers very quickly. In this video, I’ll show you in more detail how it works. I’ll also show you how to use the game to guess numbers even larger than three digits. Once you’ve mastered the strategies in this game, you’ll never lose another game of Mastermind again.

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Download Student Worksheet & Exercises

What do you think about using this method to guess 4 or 5 digit numbers? It’s not much more complicated than guessing smaller numbers, but it’s a lot to keep track of in your head. So use a pencil and paper to give it a try.

Exercises

Your exercise for this lesson is to play this game (start with two-digit numbers) until you can see a pattern to quickly guess any number. Have fun!

[/am4show]

Dictionary

Tuesday July 31, 2012

If a friend had chose a three-letter word and asked you to guess it, how would you start? It seems like it might take a while to narrow it down, right? This is a neat word guessing game that uses some strategy to make the guessing both a little easier and more fun. When you try to guess your partner’s three-letter word, they can simply give you one of two clues that will make it a bit easier to narrow down the answer. Watch the video for an explanation.

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So just by using words like “Not yet!” and “Too far!” you can make the game much more fun and interesting. Otherwise it might take a really long time to figure out the word! If you and your friends start to get really good at this game, you can try it with four and five letter words to make it even more challenging.
[/am4show]

Tic Tac Toe

Tuesday July 31, 2012

The first folks to play this game lived in the Roman Empire, but it was called Terni Lapilli and instead of having any number of pieces (X or O), each player only had three, so they had to move them around to keep playing. Historians have found the hatch grid marks all over Rome. They have also found them in Egypt!

In 1864, the British called it “noughts and crosses”, and it was considered a “children’s game”, since they would play it on their slates. In recent times (1952), OXO was one of the first known video games, as the computer played games against a person.

Tic-Tac-Toe can be fun, but when you get a “cat’s game” (no winner), it can get a little boring pretty quickly, right? In this video, I’ll show you some cool ways to change the game to make it more interesting by changing one or two of the basic rules. It’s much more engaging and strategic that way! Currently there are over 100 variations of Tic-Tac-Toe, and I’m going to show you my favorite ones. In fact, last time I taught a live science workshop, all 120 kids played this at the same time with squeals of delight!

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Which variation of Tic-Tac-Toe did you like best? Do you think it changes the game a lot to let each player choose either X or O during their turn? The number Tic-Tac-Toe game is pretty neat – I’ve found it’s easier to keep track by starting with 9 and going down to 1, alternating turns and numbers as you go. Last One Wins is great, too, but 4-In-A-Row Tic-Tac-Toe may be my favorite. It’s really fun for the whole family to play!

[/am4show]

Rail Fence Cipher

Tuesday July 31, 2012

Cryptography is the writing and decoding of secret messages, called ciphers. Now for governments these secret ciphers are a matter of national security. They hire special cryptanalysts who work on these ciphers using cryptanalysis. The secret is, solving substitution ciphers can be pretty entertaining! Ciphers are published daily in newspapers everywhere. If you practice encoding and decoding ciphers, you too can become a really great cryptanalyst.

In this video, I’ll show you how to use the Rail Fence Cipher. Before you start, say this three times fast: cryptanalysts use cryptanalysis to crack ciphers!

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How did you like the Rail Fence Cipher? Pretty neat, right? Would you rather encode or decode a cipher? I think both parts are fun. But if you’re encoding, just make sure the decoder knows the correct formula to use!

Exercises

Write the cipher of the following message:

COME TOMORROW AT 2PM
HE HAS ARRIVED AT THE AIRPORT
HE IS CARRYING A BAG
THEY ARE HERE NOW
COME AT MY PLACE

Write the cipher of the following message (use a three row zigzag)

COME TOMORROW IN MY OFFICE
LEAVE THEM BEHIND
WE WILL BE THERE SOON
The cipher below was encoded using a two rows zigzag method with six letters in every row. Decode it.
IMOIG OACMN NW
The cipher below was encoded using a three rows zigzag method with four letters in every row. Decode it.
ICINA ONOMM GW

[/am4show]

Twisted Path Cipher

Tuesday July 31, 2012

In this video, I demonstrate a Twisted Path Cipher. It uses a matrix and a path in order to encode your message. The shape of the path you create within the matrix of a Twisted Path Cipher determines how difficult it will be to break the code. Watch the video to learn exactly how it works.

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Download Student Worksheet & Exercises”

What did you think of the Twisted Path Cipher? Remember that it will be easier to break your code if you use straight lines, so consider using some extra tricks to make it more difficult. For example, spirals, and zigzags are super hard to crack, and paths don’t have to be continuous! If you’re encoding, just make sure that the decoder knows the correct path shape (or shapes) to use!

Exercises

Given the following message, what would be the best size of the table to use?

COME TOMORROW
WE ARE WAITING AT THE BUS STATION
THE LETTER IS IN HIS BRIEFCASE
HE WILL COME LATE TODAY

Identify the type of path indicated in the diagrams below

Write the cipher of the following message using the path in #5 above.

I WILL LEAVE FOR UK TODAY
AM ON MY WAY TO THE SCENE
I WILL ATTEND THE OPENNING DAY
I WILL BE THERE AT 2

[/am4show]

Shift Cipher

Tuesday July 31, 2012

Shift ciphers were used by Julius Caesar in Roman times. The key is a number which tells you how many letters you’ll shift the alphabet. These are fairly simple to encode and decode. However, you have to be extra careful when encoding because mistakes can throw off the decoding process. Watch the video to see why it’s important to double check your work!

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Do you see why it’s important to double check the encoding? This is a simple code, but it’s easy to shift and end up with a jumble when your message is decoded. So always check your cipher with a practice decoding prior to sharing it.

Exercises

Use the key shift number 4 on the letters of alphabet to code or decode the following:

Encode the following statement:

OUR SCHOOL WAS THE BEST
I WAS THE BEST IN MATHEMATICS
I AM THREE FEET TALL
OUR SCHOOL HAS GOOD TEACHERS
COME TO MY RESCUE

Decode the following:

SAWNA HAWRE JCXQZ
SDWQE OQDAM PAOQE KJXQZ
LHAWO AYKIA QKZWU
EWIKJ IUSWU
ODAEO WCKKZ OEJCA NMXQZ

[/am4show]

Date Shift Cipher

Tuesday July 31, 2012

The Date Shift cipher is a much harder code to break than, for example, the more simple Shift cipher. This is because the shift number varies from letter to letter, and also because it’s polyalphabetic (this means that a single number can represent multiple letters). I’ll explain it all in the video.

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Download Student Worksheet & Exercises

What do you think about the Date Shift cipher? The possibilities for numerical keys are endless. You can use the date you’re sending the message, birth dates, phone numbers, and more! Just remember to start decoding by writing the key numbers over the top of the encoded cipher. And always makes sure the decoder has the correct numerical key!

Exercises

Which kind of key is used in date-shift ciphers?
In which direction is the cipher shifted when decoding?
How do you describe a cipher where a specific alphabetical letter represents more than one letter?

What would be the date shift key codes for the following?

April 4^th 1998 (Don’t forget that the key needs six digits! Use “04” for the date.)
Jan. 28^th 2012
Nov. 30^th 2011

Encode the following:

COME TO MY HOME : March 16^th 1999
THEY HAVE JUST LEFT : June 1^st 2001

What are the original messages? (These messages were sent on July 16^th 1992)

GUBZC GOGNZ
MKFZV GAZTO GROZQ

[/am4show]

Pig Pen Cipher

Tuesday July 31, 2012

The Pig Pen cipher is of the most historically popular ciphers. It was used by Freemasons a century ago and also by Confederate soldiers during the Civil War. Since it’s so popular, it’s not a very good choice for top secret messages. Lots of people know how to use this one! It starts with shapes: tic-tac-toe grids and X shapes. I really like it because coded messages look like they’re written an entirely different language! Watch the video to learn how it works.

[am4show have=’p8;p9;p11;p38;p102;p154;’ guest_error=’Guest error message’ user_error=’User error message’ ]

Download Student Worksheet & Exercises

Isn’t this a fun one! To make the cipher a little harder to crack, arrange the encoded message in groups of five characters. As always, remember that your intended recipient needs the Pig Pen key in order to decode your message.

Exercises

What’s the difference between the second and the fourth pig pen?

Draw the following:

The third pig pen
The first pig pen

Using the following pig pen key, encode #4-7:

GO TO SCHOOL
COME BACK
I WILL SLEEP LATER
NORTHERN AMERICA

Using the pig pen key, decode the following messages:

[/am4show]

Polybius Checkerboard Cipher

Tuesday July 31, 2012

Polybius was an ancient Greek who first figured out a way to substitute different two-digit numbers for each letter. In the Polybius cipher we’ll use a 5×5 square grid with the columns and rows numbered. Take a look at the video and I’ll show you how it works.

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Download Student Worksheet & Exercises

To make the Polybius more difficult to crack, you can write the alphabet backwards or in an up and down pattern rather than left to right. Just be sure the decoder knows if you’ve used a different path or pattern to encode.

Exercises

Write the grid that is used to encode and decode messages in the Polybius Cipher. (Can you think up your own?)
Identify the codes representing the following letters using the grid from the example in the lesson: A, O and C.

Encode the following statements using the Polybius Cipher grid from the main lesson:

LET US LEAVE
I AM LEAVING
THEY WILL COME
SHE IS HERE

Decode the following messages using the Polybius Cipher grid from the main lesson.

32-35-35-31-11-45-45-23-15-45-11-12-32-15
24-45-24-44-23-24-14-14-15-34
23-15-43-15-24-44-45-23-15-41-11-41-15-43
32-35-35-31-11-45-33-55-12-35-35-31

[/am4show]

Cracking Ciphers

Tuesday July 31, 2012

Cryptograms are solved by making good guesses and testing them to see if the results make sense. Through a process of trial and error, you can usually figure out the answer. Knowing some facts about the English language can help you to solve a simple substitution cipher. For example, did you know that an E is the most commonly-used letter in the English alphabet? It’s also the most commonly-used letter to end a word. Watch the video below to learn some more tips and tricks to get you on the right track to being an expert cryptogram solver!

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Download Student Worksheet & Exercises

So, it helps to have a lot of words to work with so that you can begin to recognize patterns in the code. Here are some examples from the video:

single letter words will most likely be either A or I
the most frequent two-letter words in English are OF, TO, and IN
the most frequently used three-letter words are THE and AND
finally, the most frequently occurring four-letter word in English is THAT

Additional tips include the fact that Q is almost always followed by U, and that N often (but not always) follows a vowel. Finally, if two code symbols occur in a row, they could be a consonant combination such as LL, EE, SS, OO, TT, etc. The real trick to this is to try something, and then if it doesn’t work, go back and try something else. Get lots of practice by checking in newspapers and magazines for these popular puzzles. If you really like them, you can find puzzle books full of cryptograms. You’ll be an expert cipher solver in no time!

Exercises

What does it mean by “cracking a cipher?”
In there a difference between cracking and decoding a cipher?
What is very important that a person should know before beginning the cracking process?
What is the most common letter of alphabet that is usually at the end of a word?
What is the most common letter that is usually at the beginning of a word?
If you have a letter all by itself, what is it most likely to be?
What are two of the most common two character words in sentences?
What are two of the most common three character words in sentences?
What is the most common four character word in sentences?

[/am4show]

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What about years 2000-2099?

What about year codes for other centuries?

Why does this work?