What is mold, anyway?
That fuzzy stuff growing on the food in your mold terrarium
is mold, a kind of fungus. Mushrooms are one kind of fungus; molds are another.
Unlike plants, molds don't grow from seeds. They grow from
tiny spores that float around in the air. When some of these spores fall
onto a piece of damp food, they grow into mold.
Green plants are green because they contain a chemical
compound called chlorophyll. Chlorophyll makes it possible for green plants
to capture the energy of sunlight and use it to make food (sugars and starches)
from air and water. Unlike green plants, mold and other fungi have no chlorophyll
and can't make their own food. The mold that grows in your mold terrarium
feeds on the bread, cheese, and other foods. The mold feeds itself by producing
chemicals that make the food break down and start to rot. As the bread rots,
the mold grows.
Ick! Who wants this stuff around?
It can be annoying to find moldy food in your refrigerator.
But in nature, mold is a very useful thing. Mold helps food rot, which is
an icky but necessary thing. In a natural environment, rotting things return
to the soil, providing nutrients for other plants. Mold is a natural recycler.
Why does the mold on different foods look different?
There are thousands of different kinds of molds. One mold
that grows on lemons looks like a blue-green powder. A mold that grows on
strawberries is a grayish-white fuzz. A common mold that grows on bread
looks like white cottony fuzz at first. If you watch that mold for a few
days, it will turn black. The tiny black dots are its spores, which can
grow to produce more mold.
 Why didn't some foods get
moldy?
If you used foods that contain preservatives, mold may
not have grown very well on them. If you want to experiment more with mold,
you can make one mold terrarium using food with preservatives (like a packaged
cupcake) and another using food that doesn't have preservatives (like a
slice of homemade cake). Which one grows more mold? You can also experiment
with natural preservatives like vinegar and salt. If you do more experimenting,
let us know what you discover! | 
Ask a grown-up for 4 or 5 different pieces of
leftover food. If the food is small-a grape or one section of an orange-use
the whole thing. Cut bigger foods like bread or cheese into 1-inch chunks.
Dip each piece of food into some water and put
it into your container. If you use a big jar, lay it on its side. Try to
spread the pieces out so that they are close to each other, but not all
in a heap.
Put the lid on the container. Tape around the
edge of the lid to seal it.
Put the container in a place where no one will
knock it over or throw it away. You may want to label it "Mold Terrarium."
Every day, look at the food in your Mold Terrarium.
For the first 2 or 3 days, you probably won't see much. But soon you should
see blue or green or white fuzzy stuff growing on some of the pieces of
food.
After a few more days, some of the food in your
mold terrarium may start to rot and look really gross. You can watch how
the mold spreads and how things rot for about 2 weeks. After that, it'll
get boring, because not much more will happen.
