Both adult supervision and a microscope for kids are recommended.
1. Cut off the stem of a mushroom even with the cap and place the cap on a glass microscope slide with the underside down (as much of it as will fit). Cover the whole thing with a cup or bowl to keep out any drafts that might blow the spores away. Let it sit overnight.
2. The cap will drop its spores on the slide overnight. Remove it and carefully place the slide on the microscope stage.
3. Look at the spores under the microscope. At low power they will look like streaks of tiny specks; use higher power to see individual shapes.
4. Slice a very thin section of the mushroom gills from the underside of the cap and place it on a slide with a drop of water. Cover it with a coverslip and examine it under the microscope. Do you see little knobs on the gills? The spores attach to those knobs.
Try looking at spores from several different kinds of mushrooms; can you see differences between them? Molds are a type of fungus, just like mushrooms are. Try smearing a thin layer of mold on a slide and covering it with a drop of water and a coverslip. You should see thin filaments that get larger on the ends where the spores are.
Spores from mushrooms can make cool patterns.
Learn how to make a spore (and spider web) print that you can keep!