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Web of Life Unit Share
Mystery 3 of 6
Where do fallen leaves go?
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DISCUSS (1 of 2):

Where do you think all the leaves go?

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DISCUSS (2 of 2):

What could you do to find out?

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DISCUSS:

What do you think is happening in the photo below?

Where do you think the stuff growing on the fruit comes from? rotting lemons

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DISCUSS:

Imagine you were going camping for two weeks without a refrigerator and you wanted to bring some sliced oranges.

What might you do to keep the oranges from decomposing?

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You've completed the Exploration & Activity!

If you have more time, view the assessment, reading, and extension activity in the extensions.

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Extensions

Below are ideas for extending this topic beyond the activity & exploration you just completed.
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Activity: Worm Composting

Do the Rot Thing, an activity booklet produced by the Alameda County Waste Management Authority (CA), includes a section on worm composting in your classroom. Get up close and personal with the decomposers that keep our planet healthy.

Learn more about worms from University of Illinois’ online resource, The Adventures of Herman (the Worm). Available in English and Spanish.

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Readings

These Common-Core-aligned readings are free with registration on ReadWorks. All include comprehension questions.

The ancient Egyptians made mummies by using salt to keep mold from growing. Read about animal mummies in Pet Cemetary. (grade 5)

Learn how people kept food cold before they had refrigerators in Ice Harvest. (grade 6)

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Video: When Good Food Goes Bad

These dramatic time-lapse videos show what happens to fruit as it molds.

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Video: Indiana Jones of fungus hunters

Dr. Gary A. Strobel is known as the Indiana Jones of fungus hunters. He searches the world’s forests for fungi that live inside plants. Many of these fungi produce chemicals that protect the plants from disease and infection. In the laboratory, Strobel tests these chemicals to see if they can be as useful to people as they are to the plants that they come from. By doing this, he has found chemicals that save lives.

To learn about his work, watch from 35:30 to 37:40 in Nature’s Great Decomposers, a 45-minute documentary on NatGeo TV.

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FAQ

Looking for answers to some frequently asked questions about mold? You've come to the right place.

These answers are from the Mad Scientists Network, a collective of smart scientists who aren't really mad at all.

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Discuss: Science & History

How did people keep food from spoiling before they had refrigerators? Ask your students for ideas. Here are some questions to get them thinking — with links for further research.

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Image & Video Credits

Mystery Science respects the intellectual property rights of the owners of visual assets. We make every effort to use images and videos under appropriate licenses from the owner or by reaching out to the owner to get explicit permission. If you are the owner of a visual and believe we are using it without permission, please contact us—we will reply promptly and make things right.

Exploration
leaves on cement by Kichigin
walking through leaves by Suzanne Tucker
kid playing in leaves by Chris Nolan , used under CC BY
wintery road by David Merrigan , used under CC BY
spring/green road by artens
bag of leaves by MiVa
leaves by Albert Bridge , used under CC BY-SA
walking on log-leaves by unsplash
leaf decomposition by Josh Williams
fungus mycelium by Kris H. Light
second log flip by Sergei A. Polozov
growing mycelium by franchise films
mushroom time lapse by OddScience
mushroom time lapse 2 by franchise films
fungi mycelium on wood by chanus
hands dug into work by 13Imagery
decomposition by StopWaste
Russula by Jerzy Opioła , used under CC BY-SA
cinnabar-red chanterelle by Jake Stookey
red capped mushrooms by Gemini78
yellow & white capped mushrooms by Kurt Bauschardt , used under CC BY-SA
mushroom by Mary Smiley , used under CC BY-SA
white mushroom by arhendrix
orange mushrooms by Mushroom Observer , used under CC BY-SA
Cordyceps_locustiphila_Henn by Mushroom Observer , used under CC BY-SA
mycelium growing more by Jerzy Opioła , used under CC BY-SA
trees broken up by shore by skeeze , used under Public Domain
man hiking by Poprotskiy Alexey
mushrooms growing outside complex by Vasile Cotovanu , used under CC BY-SA
forest floor by Alessandro Colle
pinic table lunch by adriaticfoto
moldy bread by Taborsky
moldy strawberries by rsooll
mycelium on potato by Telia
mycelium in orange substance by Irina Kozorog
moldy orange by Irina Mos
mushroom cap by Aleksey Gnilenkov
casual living room by Wonderlane
berry decomposition by webiocosm
compost bin by Evan Lorne
inside of compost bin by BMJ
woman inside grocery store by Adam Melnyk
moldy tomatoes by Comrade Foot
inside of fridge by thodonal88
camping- tent by Milaniphotography
Activity
black electric heater by ronstik
hands by photka
pencil by JohannPoufPouf
hands up by Rawpixel.com
Other
Unit: leaf by LilKar
Unit: leaf 2 by Etakundoy
Overview
Grade 5th
Topic Ecosystems & The Food Web
Focus Decomposers & Matter Cycle
Print Prep
Activity Prep

In this Mystery, students discover the role fungi play in decomposing dead materials and in creating soil. In the activity, Mold Terrarium, students plan and conduct an investigation to discover the factors affecting decomposition. Students fill Ziploc bags with different types of foods and change environmental conditions to study how different variables affect mold growth. They then observe mold growth over a period of two weeks.

Preview activity

Number of students:
Clean-up Supplies (Eg. Paper Towels)
1 roll
Cutting Board
1 board
Knife
1 knife
Additives to Inhibit Mold Growth
Salt, sugar, and hot pepper work well.
Details
8 tablespoons
Day-Old Loaf of Bread
Ask at a bakery or grocery store for day-old or expired bread.
Details
1 loaf
Duct Tape
1 roll
Fruit
You will need this number of slices for each type of fruit that you are using. Our lesson shows a slice of apple, orange, and banana in each mold terrarium, but you can choose whatever fruit is easily available. Oranges and strawberries both mold well.
Details
8 slices
Solo Cups (9 oz)
8 cups
Sticker Labels (1" x 3")
The label needs to be large enough so that students can write their team name, the date, and the starting conditions of their mold terrarium.
Details
8 labels
Thick Paper Plates
Used as the experiment control.
Details
1 plate
Thick Paper Plates
The plate must be small enough to fit inside the Ziploc bag. You will throw out the plate and bag when the experiment is done. Plastic plates will also work.
Details
8 plates
Ziploc Bags (Gallon)
Used as the experiment control.
Details
1 bag
Ziploc Bags (Gallon)
The bag must be large enough to hold the paper plate and still be sealed.
Details
8 bags
Mold Terrarium printout Print 30 copies
Prep Instructions

You will need access to water for this activity.

In addition to the supplies listed above, you will need a well-ventilated area to store your mold terrariums. The space you have available may limit how many terrariums you make.

Each mold terrarium will be sealed in a Ziploc bag that is then sealed with duct tape. Students will observe mold through the clear plastic, but will not open the bags. When your observation period is over, you will throw the entire experiment away. Do not open the bag. Opening the bag would release mold spores, which can exacerbate asthma and cause respiratory illness.

We suggest students work in groups of four. Homeschool students can work on their own.

Plan Your Time

You may want to divide this activity into two sessions.

Part 1 (students brainstorm ideas for their mold terrarium) takes 10 to 15 minutes.

Part 2 (students set up their mold terrariums) takes 15 to 20 minutes.

If you plan to do the activity in two sessions, Part 2 begins at Step 7.

Decide What Variables Students Will Test

In this activity, each group of students decides on ONE condition to change — that is, one way that their terrarium will be different from the basic terrarium, which contains only damp food kept at room temperature. They may choose a condition that they think will encourage mold growth (e.g. heat) or one that they think will inhibit it (e.g. preservatives such as salt, sugar, or hot pepper). So you may want to think ahead regarding what materials or conditions (hot vs cold) you can accommodate in your classroom.

If you divide the lesson as discussed in “Plan Your Time,” you have the option of bringing in additional materials for Part 2 when students set up their terrariums and test different variables.

Students may suggest adding garden soil or compost to the food to encourage mold growth. Don’t do it! Some soil bacteria (known as anaerobic bacteria) make nasty smells when they break down foods. These anaerobic bacteria thrive in a sealed plastic bag with water and fruit. A mold terrarium with soil will grow mold — but it will also stink!

Prepare Food Items Before Class

Before class, cut up the food that you will be using in your experiment. In our lesson, we include a half slice of bread, a piece of cheese, a slice of apple, a slice of orange, and a slice of banana. You can use whatever food items are easily available, but include the same items for each terrarium and try to make them the same size to ensure a fair test. For each team, prepare a paper plate with a piece of each kind of food that you’ll be testing. Here’s an example of what our plates looked like:

Mold Terrarium Food Items

Make a Basic Mold Terrarium to Use as a Control

You will need to make a basic terrarium that contains damp food at room temperature. This basic mold terrarium will serve as the control so students can compare their experimental results to it. To see how to set this up for yourself, follow our step-by-step instructions (Steps 7 through 12) here. [Note: If you plan to teach the lesson in two parts, wait to prepare your terrarium right before you teach Part 2.]

Get Duct Tape and Water Ready

Each group will need a cup filled with water so that they can moisten each of their food items, and will also need a strip of duct tape longer than the width of the Ziploc bag so they can double seal the bag. You may want to prepare these supplies prior to class to make distribution easier.

Separate Supplies for Easy Distribution

In Part 1, students will only need their Mold Terrarium printout and a writing utensil.

In Part 2, each group will need the following supplies:

Mold Terrarium Supplies

You may want to separate these supplies to make classroom distribution easier.

Observe Mold Terrariums for Two Weeks

The second page of the student handout lets students record observations of their terrarium over time. This lets them see which food molds the fastest in their terrarium. By filling in circles to record how much of a given food is covered with mold, they create a bar graph of the mold growth.

We recommend creating a bulletin board where all teams can record and compare results for their terrarium. By comparing results, students can look for patterns and observe which conditions are most conducive to mold growth. They can then answer questions like:

  • Does the same food mold the fastest in all conditions?
  • If you had to take food on a long trip and you had no refrigeration, which of these foods would be the best one to take? How would you store it to keep it fresh as long as you could?
Overview
Grade 5th
Topic Ecosystems & The Food Web
Focus Decomposers & Matter Cycle
Extensions