Slide Preparation: Staining

Make sure you’ve completed the How to Use a Microscope and also the Wet Mount activities before you start here!

If your critter is hard to see, you can use a dye to bring out the cell structure and make it easier to view.  There are lots of different types of stains, depending on what you’re looking at.

The procedure is simple, although kids will probably stain not only their specimens, but the table and their fingers, too.  Protect your surfaces with a plastic tablecloth and use gloves if you want to.

We’re going to use an iodine stain, which is used in chemistry as an indicator (it turns dark blue) for starch. This makes iodine a good choice when looking at plants. You can also use Lugol’s Stain, which also reacts with starch and will turn your specimen black to make the cell nuclei visible. Methylene blue is a good choice for looking at animal cells, blood, and tissues.

In addition to your specimen, you’ll need to get out your slides, microscope, cover slips, eye dropper, tweezers, iodine (you can use regular, non-clear iodine from the drug store), and a scrap of onion. If you can find an elodea leaf, add it to your pile (check with your local garden store). Here’s what you do:

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10 Responses to “Slide Preparation: Staining”
  1. robertdangelo says:

    Hi Aurora, it’s Andie. I want to look at river water under a microscope, mainly because I’m sure that there are all kinds of little creatures in there. However I am almost certain that I will need to stain it, but I don’t want to kill all the organisms in there. Will ordinary food coloring do the trick?

    Andie D’

    P.S. Please respond soon.

    ~ Andie

  2. Aurora says:

    Dish detergent or ethyl alcohol should do the trick. The slide covers are harder to clean since they are so thin. If the slides are old and dirty, soak them in warm water with detergent overnight, and then wipe them clean with a towel. Wrap the slides in paper until you’re ready to use them again.

  3. Shannon Hamrick says:

    This may seem like a silly question. but what is the best way to clean the slides after using them? Just soap and water or do we have to do anything special? What about the slide covers. Do we just throw those away?

  4. Aurora says:

    I’ll have my team connect with you right away!

  5. Laura Sigley says:


    I am having the same problem as Eric Christiansen. Thanks, Laura

  6. Aurora says:

    We’ll check into this right away, and if there’s an issue with your account my team will get right back to you! Sorry for the trouble.

  7. Tara Pearne says:

    We are also having difficulty completing the 7th grade activities for the Life Science unit.

  8. Aurora says:

    You simply request to get access, and poof! It should happen automatically. I’ll check those particular posts to see if there’s a glitch somewhere. Check back soon and let me know if it’s still an issue.If there are any others, let me know as well. Make sure you log out, then log back in when you check back. Thanks!

  9. Christina Feinberg says:

    I am having similar difficulties in that I’m blocked from the ‘how to use a microscope’ and ”wet mount’ activities. I would very much like to be able to progress through the curriculum for my 7th grader. What do I need to do? Thanks, Christina

  10. Eric Christiansen says:

    Hi, I am trying to navigate the site and preplan my lessons. My problem is that in looking at the 7th grade activities, in order to do the experiments for the Life Science unit, we are to have completed the How to Use a Microscope and Wet Mount activities. However, when I attempt to access those, I get the ‘sorry this is in 9-12th grade content’ message. Again, I am in Life Sciences section under 7th grade level. Please help! 🙂 Thanks, Ramona

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