Composting Lesson Plan 3-6th Grade

Trash in the Soil Experiment

By Darci Pauser

This experiment will get students thinking about the breakdown (or lack thereof) of materials that humans produce. It also explores the concepts of organic and inorganic matter, as well as the presence of agents of decomposition such as moisture and microorganisms.

You will need:

One large yogurt container for each student

Soil from the ground (not potting soil! no microorganisms!)

All about 2cm by 5cm or so of:

Pieces of plastic (cut up plastic bag, cut up plastic cup)

Pieces of metal (bottle caps, coins)

Pieces of paper bag

Kitchen food scraps

Introduce the experiment through a discussion of trash. What do we use? What do we throw away? What do you think you throw away the most? Where does it go? Do you recycle?

What things do you recycle?

The students will probably answer bottles and cans and paper. Write them on the board and ask them what these objects are made of. What are bottles made of? Next to bottles, write glass and plastic. What is used to make glass and plastic? Explain that sand and oil are the raw materials used to make glass and plastic and write sand and oil on the board. What is used to make paper? Trees.

(the recyclable material “cootie-catcher” may be incorporated into this lesson)

Explain that trash items fit into two categories of organic (paper and food scraps) and inorganic (glass and plastic). Organic means “living or once living,” while inorganic is “nonliving”—it never lived at all.

You may show the students the book “Tracking Trash: Flotsam, Jetsam, and the Science of Ocean Motion” to prompt discussion on the ways in which scientists study trash.

Explain that you would like to see what happens to trash in the ground and in a landfill. Ask the students how they would do this experiment.

Suggest that the students bury different kinds of trash (organic and inorganic) in soil. Pass out the containers, and small cups filled with soil. Pass out a piece of each trash material to the students. Have them write down the materials in their experiment under “Organic” and “Inorganic” columns. Next, distribute another cup of soil to the students, covering all the trash materials. Finally, the students should moisten the soil with water, just enough to get the trash damp.

Ask the students what they think will happen to the trash. Will anything change in any way in one month? Will there be a difference in what happens to the organic and inorganic material?

Explain that in a landfill, there is a lot of trash and not a lot of soil, so the trash does not get much air—particularly oxygen, and this is called “anaerobic” (the soil provides an aerobic environment). Ask the students how they can perform an experiment that will show what happens to trash in an anaerobic environment. Suggest that they put the same trash in a sealed jar.

Distribute jars with lids, some soil, and trash material to each student. Have them record the items in their experiment and predict what will happen to the materials.

Water the open-air containers every week for 4 to 6 weeks.

At the end of the experiment, have the students dump out their containers to see what happened to each material. The plastic and metal should be generally unchanged, while the paper and food scraps should be decomposing.

Do not open the jars, but have the students observe what occurred in the jars compared to the aerobic environment of open-air soil. Discuss with the students the formation of methane gas from the rotting of organic material in an anaerobic environment, and the inability of nutrients from organic material to return to the soil in landfill environments.

Reflection Questions:

Why did the organic material break down? What helped it? (water, microorganisms)

Did you see any organisms in the soil? (can’t see microorganisms, but they may have seen bugs)

How long do you think it would take for the inorganic material to break down?

How can our landfills be improved? (compost organic material, recycle as much as possible)

Do you think we could live without landfills completely?

If a farmer wanted to grow food on an old landfill, what problems do you think she would run into?

Trash in the Soil Experiment

By Darci Pauser

This experiment will get students thinking about the breakdown (or lack thereof) of materials that humans produce. It also explores the concepts of organic and inorganic matter, as well as the presence of agents of decomposition such as moisture and microorganisms.

You will need:

One large yogurt container for each student

Soil from the ground (not potting soil! no microorganisms!)

All about 2cm by 5cm or so of:

Pieces of plastic (cut up plastic bag, cut up plastic cup)

Pieces of metal (bottle caps, coins)

Pieces of paper bag

Kitchen food scraps

Introduce the experiment through a discussion of trash. What do we use? What do we throw away? What do you think you throw away the most? Where does it go? Do you recycle?

What things do you recycle?

The students will probably answer bottles and cans and paper. Write them on the board and ask them what these objects are made of. What are bottles made of? Next to bottles, write glass and plastic. What is used to make glass and plastic? Explain that sand and oil are the raw materials used to make glass and plastic and write sand and oil on the board. What is used to make paper? Trees.

(the recyclable material “cootie-catcher” may be incorporated into this lesson)

Explain that trash items fit into two categories of organic (paper and food scraps) and inorganic (glass and plastic). Organic means “living or once living,” while inorganic is “nonliving”—it never lived at all.

You may show the students the book “Tracking Trash: Flotsam, Jetsam, and the Science of Ocean Motion” to prompt discussion on the ways in which scientists study trash.

Explain that you would like to see what happens to trash in the ground and in a landfill. Ask the students how they would do this experiment.

Suggest that the students bury different kinds of trash (organic and inorganic) in soil. Pass out the containers, and small cups filled with soil. Pass out a piece of each trash material to the students. Have them write down the materials in their experiment under “Organic” and “Inorganic” columns. Next, distribute another cup of soil to the students, covering all the trash materials. Finally, the students should moisten the soil with water, just enough to get the trash damp.

Ask the students what they think will happen to the trash. Will anything change in any way in one month? Will there be a difference in what happens to the organic and inorganic material?

Explain that in a landfill, there is a lot of trash and not a lot of soil, so the trash does not get much air—particularly oxygen, and this is called “anaerobic” (the soil provides an aerobic environment). Ask the students how they can perform an experiment that will show what happens to trash in an anaerobic environment. Suggest that they put the same trash in a sealed jar.

Distribute jars with lids, some soil, and trash material to each student. Have them record the items in their experiment and predict what will happen to the materials.

Water the open-air containers every week for 4 to 6 weeks.

At the end of the experiment, have the students dump out their containers to see what happened to each material. The plastic and metal should be generally unchanged, while the paper and food scraps should be decomposing.

Do not open the jars, but have the students observe what occurred in the jars compared to the aerobic environment of open-air soil. Discuss with the students the formation of methane gas from the rotting of organic material in an anaerobic environment, and the inability of nutrients from organic material to return to the soil in landfill environments.

Reflection Questions:

Why did the organic material break down? What helped it? (water, microorganisms)

Did you see any organisms in the soil? (can’t see microorganisms, but they may have seen bugs)

How long do you think it would take for the inorganic material to break down?

How can our landfills be improved? (compost organic material, recycle as much as possible)

Do you think we could live without landfills completely?

If a farmer wanted to grow food on an old landfill, what problems do you think she would run into?
How was the jar experiment different from the open-air one?

Why did we use sealed jars? (anaerobic environment)

What’s wrong with organic material breaking down in an anaerobic environment? (anaerobic bacteria produce methane)

How was the jar experiment different from the open-air one?

Why did we use sealed jars? (anaerobic environment)

What’s wrong with organic material breaking down in an anaerobic environment? (anaerobic bacteria produce methane)

the Search for Soil

Trying to garden in Oakland is like training a housecat to ride a bike. The waitlist for the city-run garden plots is too long to cope with, and the city does not exactly encourage the creation of new such community gardens. My back porch is choked with containers growing tomatoes, strawberries, bean sprouts, chard, mustard greens, and lemon verbena, but the containers do not satisfy the urge to get one’s hands deep into the soil, and the plants are also not so satisfied with this restriction.

The front of my apartment building is donned with two plots of plant space, each around 10 by 25 feet. All the plants (except for what seems t0 be a volunteer cilantro plant in its flowering stage) are typical lets-just-cover-some-space landscaping plants. Granted, some of the flowers are gorgeous and much-needed, but even still, I held that this small parcel of earth could be put to work to satisfy some basic subsistence needs as well as psychological contentment. 

The plots are covered in life-suppressing mulch where the landscape plants do not grow. Upon observing some of these in-between places, I decided to utilize them for gardening purposes. In went my other lemon verbena cutting, in went a squash, some broccoli (i know, not the season, but my roomie sprouted them for whatever reason), in went a pumpkin (also, roomie, is it really the season?), and in went a tomatillo. At another interstice, in went a tomato transplant, in went melon  and bean seeds. The other day, in went three cukes and an eggplant. 

Back to the training cats to ride bicycles, the apartment manager came out to walk her dog and discovered me watering the newly transplanted tomato plant. She said accusingly, “What are you doing?”

“I’m planting a tomato plant!” I replied in an excited and naive tone. 

“But I don’t think this is your property.”

“It belongs to the building, doesn’t it?”

Shaking her head, “I don’t know, I don’t know, I will ask the owner.” I didn’t hear anything more about it, and so far, my babies are intact. I painted on a brick ‘Garden Please Do Not Disturb’ to mark one spot.

The owner of the building, by the way, is a faceless corporation. So nice to feed the usurers, while others do all the work (the managers– I am sympathetic despite the excessive grumpiness). 

When I left the farm to return to Oakland, I knew my gardening capabilities would take on this character, and that I would be forced to plant in the overlooked extra spaces that do not exist as one large swath, but rather as a collection of interstices that demand a different set of strategies of locale and care, and involve education (training, if you will) of the residents in new values and aesthetic standards.