Putting the "fun" in "fungus"

Encourage your child to develop skills of observation with this moldy experiment.

By Dr. Fred Stein, Consulting Educator

Transform your kitchen into a kid-friendly laboratory with a simple slice of bread. Using everyday materials, you can pique your budding scientist’s interest in experiments by growing various types of mold and having her make detailed observations, noticing both similarities and differences. As she tracks changes over time, she can look for patterns and uncover the fascinating world of bacteria.

What you'll need

Sliced white bread without preservatives (check the ingredients for sodium propionate)
Sandwich-size Ziploc bags
An eyedropper or a teaspoon
A Sharpie pen

How to do it

Preservative-free bread is a wonderful medium for producing mold, which grows from spores (the mold equivalent of plant seeds) that are already present on the bread. Your child can also collect mold and bacteria from any surface by rubbing a slice of bread on it.

To grow your own mold garden, put five to ten drops (or one teaspoon) of water on a piece of bread and store it in a Ziploc bag in a warm place. After a week, you should notice fuzzy white, black, orange, or green spots on the bread. The green variety is typically a mold called Penicillium (from which penicillin is made). Once visible, the mold will become noticeably larger each day.

Experiment with collecting or culturing mold from various places with bread slices. Even clean-looking places are covered with bacteria. Does your child think the yuckiest places will grow the yuckiest fungus the fastest? Have her record on the Ziploc bag where the mold came from. To avoid odors, keep the bags in sealed plastic containers. Try to avoid opening the bags when you dispose of them because some people can have allergic reactions to mold.

Check out the Science Museum of Minnesota’s Grow-n-Show Gallery for examples of mold.

Dr. Fred Stein is a science educator at the Exploratorium Institute for Inquiry, a national science-education-reform project based in San Francisco.