Mold Terrarium
Summary:
Grade Level: 4-8
After a short introductory game explaining the role of fungi as
decomposers, students will create their own “mold terrariums” (using common
food items, water, and yeast). They will let these “grow” in a dark place for a
week, and return to see the results!
Objectives/ Standards:
The students will…
1) Participate in a lesson/ activity about the role of fungi in the environment.
2) Design experiments to test the growth of fungi on common food items.
3) Examine the results of their experiments to learn more about fungi.
Background:
A nutrient is a substance required for life, but which cannot be created by
the body, and so must be taken in from the environment. When a living animal or
plant dies, its nutrients remain trapped within the body, but not forever. If nutrients
became trapped forever when an animal died, our world would quickly become
nutrient poor, and inhospitable further life. Thankfully, nutrients are constantly
cycled through the environment, from dead matter back into living matter, by fungi,
bacteria, and other small critters that help decompose dead organic matter and
reintroduce the nutrients into the food chain.
Fungi are everywhere, particularly where organic matter is plentiful. There
are about a million fungi in one ounce of rich topsoil. Fungi include mushrooms,
brackets, puffballs, truffles, molds, and yeast. The mushrooms and toadstools we
usually see are the fruiting, or reproductive, structures of the fungi (like the flowers on
plants). But unlike plants, fungi don’t produce seeds. Instead, they reproduce from
spores contained in the fruiting bodies. These spores float through the air and land
on stuff. When one lands on a damp piece of food, the fungus grows as it consumes
the organic matter of its host. The fruiting bodies we typically see are only a very small
part of a much larger non-reproductive network of fungal filaments (mycelium)
found within the soil or decaying matter.
Unlike plants, fungi do not contain chlorophyll and cannot change sunlight
into carbohydrates (food), so they must feed on other organisms. It is through the
mycelium that a fungus absorbs nutrients from its environment, such as dead plant
and animal matter. The mycelium of “mycorrhizal” fungi can form a mutually
beneficial relationship (mutualism) with surrounding plants, which increases the
efficiency of water and nutrient absorption to plants, and even confers resistance to
some plant pathogens! How? The fungi attach to plant roots underground to gain
access to carbohydrates which it cannot produce on its own, and this in turn gives the
plant access to the increased absorptive powers of the mycelim, especially phosphates.
Essential Questions:
 What role do fungi play in sustaining life on earth?
 How are fungi different from plants?
 How are nutrients constantly cycled through the environment?
Duration: 40 min
Indoor/ Outdoor/ Both:
Key terms:
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Fungi
mycelium
decomposers
mold
yeast
spores
nutrients
cycle
food chain
mutualism
Materials:
o Variety of food items
(breads, cheese, fruit,
with preservatives and
without)
o Clear containers (plastic
baggies or liter bottles
cut open work fine)
o Yeast (optional)
o Tape
o Water
o Permanent markers
o Newspaper
o
o
Notes:
 Do not use meat or fish,
as they will become very
smelly!
Set-up:
a. Have table space prepared for students to work with food and water.
b. Have a space prepared for students to play a semi-active game involving moving around and making silly
noises!
Lead-In:
Introduce the Nutrient Cycling Game where nutrients are passed from plants  animals fungi 
plants, by means of winning games of rock-paper-scissors (RPS).
RULES:
Students play the role of nutrients which are being constantly cycled through the environment. Students mill
around the playing area (classroom) playing RPS with each other in order to change status from (be taken up
by) plant to animal to fungus.
Each student starts as nutrients in a plant (ask them to think of their favorite plant and act like it), and must
win a game of RPS in order to be taken up by an animal (ask them to think of their favorite animal and act like
it).
Students must again win RPS to advance to be taken up by fungi (act like a mushroom?).
Students may only play RPS with someone of an equal status (fungi vs. fungi, etc), and the loser stays at the
same level.
When students advance beyond fungi status they again become plants, because many fungi pass nutrients to
plants. Notice there is no top status – because this game is meant to demonstrate a cycle!
When everyone has gone through the cycle several times, end the game. Have students return to their seats.
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The Activity:
1.
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Explain that you are going to be making terrariums to grow fungi. What will they
need to survive? Explain how fungi are very different from plants (see Background).
Assign students into groups of 2-4. Seat groups around a table and supply newspaper,
water, and clear containers.
Allow students to choose 1 food item to place in their container. Have them lightly
moisten dry food items before putting them into a container.
Optionally, have students add a PINCH of yeast to their container.
Have them seal their containers well and write a namezz and date on it.
Store in a dark place until next week…
*If time allows, you may want to encourage groups to experiment with 2
different variables.
Ex: Groups could create 2 containers that are identical, except:
 1 has water, 1 does not, OR
 1 is kept in the dark, 1 in the light, OR
 1 has yeast added, 1 does not, OR
 1 with air, 1 with air removed, etc…
Wrap-up (how will you help students “bring it home”?):
a.
One week later, have students compare and contrast their containers.
a. What color/ texture is the mold?
b. What foods got moldy quickest?
c. Did anything not get moldy?
d. Do different types of molds grow on different types of foods?
e. Which decomposed the most/ least?
f. Which showed the greatest growth of fungi (mold)?
g. Were their predictions right or wrong?
h. How can you keep your food fresh?
i. Do fungi like to eat preservatives?
b. Do not open the containers, just throw them away. Mold is not healthy to inhale.
Extensions (Where can students/ teachers go from here? What lessons could come next?):
A. Bacteria at Work – a lesson comparing rates of bacterial growth on potato wedges buried
under soil.
B. Compare rates of plant growth with and without fungal relationships. (Mycorrizal spores can
be obtained online or at garden centers).
C.
Relevant Books:
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Other Relevant Activities/ Games:
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Notes: