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The Case of the Invisible Invaders

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Learning area: Science, Health
Prep: 10 minutes
Time commitment: 40 minutes (10 minutes prep, 30 minutes activity)
Best for: Kindergarten, Grade 1, Grade 2


Introduce students to the idea that microscopic creatures called microbes, or germs, can cause illness.





  1. Have students read The Case of the Invisible Invaders handout.
  2. Ask students to name some things that they know are there, even though they can’t see them, such as air. Then, ask them to explain what evidence indicates these things exist even though they can’t see them.
  3. Invite students to examine an area, such as a countertop or their desks, that is frequently touched by hands. Ask them if the area looks clean. Have them draw what they see on their handouts, and then discuss their observations.
  4. Show students a microscope image of a microbe:

    Ask students to describe what they see and to guess what it might be.

  5. Explain that microbes, or germs, are living creatures that are so tiny you have to use a microscope to see them. Point out that the image they are looking at was taken with a microscope, making it hundreds of times larger than the actual microbe. Clarify that these microbes could be all over the area they just examined, but couldn’t be seen. If possible, show students a microscope and allow them to look through it.
  6. Show students additional images of microbes and discuss how some, like intestinal bacteria, are helpful and can cause us to get sick.
  7. Have students complete the handout by drawing what they saw with their eyes and under the microscope. Then, have them complete the Case Report describing what they learned about germs.
  8. On a separate paper, have students draw a cartoon to teach someone else about microbes, or germs.


Interactive Whiteboard Extension

  1. Create a T-chart labeled “Friend” and “Germ.”
  2. Post images of microbes one at a time and describe what each one does.
  3. Have students come up and sort each image into the appropriate column.

Originally posted 2021

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