How Does Mold Grow?
© Contributed by Leanne Guenther
This experiment uses 4 samples to test what conditions mold grow the best
in. Depending on the age of the child(ren) you can use only 2 or 3 samples instead of all 4.
What you need:
- bread (4 slices)
- saran wrap (or some other air tight covering)
- 1 to 2 weeks of experiment time
- Optional: Magnifying glass
- Optional: Molds Printable Information Sheet
- Optional: Molds Printable Activity Sheets (page
1) (page 2) (page
3) (page 4)
- I prefer to print page 1 as many times as the children need.
They can mark the date and sample number on each page. This allows
them to draw the results.
- But, it is a fair amount of work, so you may prefer to use Pages 2
thru 4 instead so they can just jot down what they see, perhaps using
page 1 on the last day of the experiment.
- Some people are allergic to molds. If this is a concern, skip
the first sample (just use the last 3) and seal each of them in a
clear glass jar, so the child(ren) can examine them without being
exposed to the molds.
- SAMPLE 1: Take a piece of bread and slice it in half (it can be a few days
old, but ensure it isn't too stale). Seal one half in saran wrap
and expose the other to air.
- SAMPLE 2: Take another piece of bread and slice it in half. Leave one
half in the dark (a paper bag or cupboard) and the other half in
strong light (sunlight works)
- SAMPLE 3: Take a third piece of bread and slice it in half. Keep one
half very dry and put about 1 tsp of water on the other half. (Spritz
the wet piece with a few drops of water each day).
- SAMPLE 4: Take a fourth piece of bread and put half of it someplace warm, in
the dark (on top of the fridge in a paper bag) and the other half
someplace cold in the dark (the refrigerator).
- Examine the samples each day with your naked eye or a magnifying
glass and record any changes in appearance.
Molds will develop on some of the samples.
Molds grow best in warm, dark and moist conditions.
In the first sample, the sealed bread should develop mold more slowly than
the unsealed bread.
In the second sample, the bread kept in darkness should develop mold more
quickly than the bread kept in light.
In the third sample, the moist bread will develop mold more quickly than the
In the fourth sample, the mold in the warm place should develop mold more
quickly than the bread in the cold place.
Questions to Ask:
- Where and how should bread be stored to keep it free from molds?
- What other foods do you think might grow molds if left exposed?
- What are some ways that people use to preserve their food?
- someplace sealed, in the refrigerator, in the light, someplace dry,
- cheese, oranges, tomatoes, lemons, onions, used coffee grounds,
potatoes (determining what foods mold the best can be an entirely
- refrigerator, artificial preservatives, natural preservatives like vinegar
and salt, tupperware