Mold is a slimy and sometimes fuzzy substance that grows in dark, moist places. And although it’s “icky” and can cause a range of health problems in some cases, mold plays an essential role in nature and science.

Molds are microscopic fungi, and they can grow wherever food, moisture and oxygen are present. That’s virtually everywhere! Molds reproduce by releasing tiny spores that float through the air, both indoors and outdoors. If the spores land on a surface with the right condition (moisture and nutrients), mold will form.

Although mold growth in the home should not be allowed, there are positive uses of molds in both nature and science:

  • Molds cause the decomposition (breaking down) of organic material, releasing and recycling nutrients.
  • Molds are used to make cheese, soy sauce, certain kinds of teas and sausages and other foods and beverages.
  • Molds are used to make citric acid, an ingredient in many foods and beverages.
  • The “wonder drug” penicillin is made from mold.

In this science experiment, students will start a mold garden and watch the mold grow. They will also learn the benefits and uses of mold as they grow and observe mold on bread.



Before beginning the experiment, ask students if they have ever seen moldy bread or fruit. Call on volunteers to describe what the mold looked like.

  1. Have students moisten a slice of bread with water and place it on a plate. Make sure the bread is damp but not soggy.
  2. After about an hour, have students cover the plate with the glass jar or bowl and place it in a dark place.
  3. Repeat the process with additional bread slices (from different types of bread) if you wish to conduct experiments and observe if mold looks/grows differently on different kinds of bread.
  4. Observe the bread daily. When grey or blue patches appear, mold has begun to grow.
  5. Allow students to use the magnifying glass to examine the mold more closely.
  6. Each day, observe and discuss the changes in the growth of the mold. Have students keep a daily observation journal of the changes they observe.

Wrap up the activity with a few discussion questions. How does the bread mold look the same or different from other molds they’ve seen? How long was it before the bread mold was first visible? When was the mold first visible through the magnifying glass? With this experiment, students will understand how mold forms and how it’s used in the environment and science.

This activity has been adapted from After-School Explorations: Fun, Ready-to-Use Activities for Kids Ages 5-12