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Composting With Worms

A Composting Experiment Demonstrates Why Worms Are "Nature's Recyclers"

from Education World ®

Subjects: Science, Social Studies

Grade Levels: PreK-2, 3-5, 6-8, 9-12

Objectives
Students will:

predict what will happen in two (control and experiment) containers -- one with soil and trash, the other with soil, trash, and worms;
learn why some people call worms "nature's recyclers"; and,
discuss how worms can help solve environmental problems.

Keywords
Worms, earthworms, recycle, compost, garbage, trash, biodegradable

Materials Needed

two see-through plastic containers of the same size, with lids (optimum container size might be a foot square and 6 inches deep); air holes should be punched in sides and lid of container
earthworms (See Purchasing Earthworms section below.)
garbage items: chopped carrots work well for this activity, since their bright color contrasts with the soil; other possible items include apple pieces or shavings, coffee grounds, and crushed eggshells.
student journals (optional)

Procedure

In this experiment students observe firsthand how earthworms transform garbage into compost.

Start with two see-through plastic containers of the same size; the containers should have lids. (One large tub, divided in half with a plastic separator, is an alternative.) Punch small air holes in the lid of the container and along the sides. Spread about 2 inches of rich soil in the bottom of the container. Spread over the top of the soil some common garbage items. Chopped carrots work well for this activity; if you arrange some of the garbage so you can see it through the container, you should be able to observe daily changes. Other items that might be appropriate include apple pieces or shavings, coffee grounds, crushed eggshells... Do not use meat or dairy products because they will smell bad.

Be sure each container contains equal amounts of soil and garbage items.

Cover the selected garbage with two inches of soil. Then add earthworms to one container only (or to one side of a divided container). For a container this size, a few dozen worms should suffice. (See Purchasing Earthworms section below.) The container without the worms is the control for this experiment. You might ask students to record in their journals predictions about what will happen to the two containers over the next couple of weeks.

Notes: Wet the soil to keep it slightly damp. Do not over water. You do not want water collecting in the bottom of the container. When not being observed, it is best to keep the container(s) in a dark place, such as a closet, because earthworms will shy away from light. Learn more tips for composting on the Worm Composting page.

During the next two weeks, observe and compare changes in the control and the worm-filled containers. If you cannot see through the containers, gently dig up the garbage after two weeks.

After Two Weeks...

Discuss the results of the experiment. What happened to the trash in the container with the worms in it? in the container without worms? How did changes in the two containers differ? Why? (Earthworms "digest" the garbage and soil, producing richer soil.) How can worms help cut down on trash?

Consider setting up a composting bin at your school. See articles on that topic in the Related Articles section below.

Assessment

Ask students to write a paragraph describing what they learned from the experiment. For younger students, you might provide several word prompts that they must include in their paragraphs; for example, worms, compost, and recycle.

More Earthworm Composting Lesson Plans

Fun Earthworm Resources to Share

Purchasing Earthworms

For information about earthworm purchases, contact a local garden shop or plant nursery, the cooperative extension division of a nearby university, a local bait and tackle shop, your city's sanitation department, a local 4-H Club, or another appropriate organization.

The worms you want to purchase are known as "red worms" or "red wigglers."

If you reach nothing but dead ends in your local community, you can find worm sources on the Internet. An excellent starting point might be The Open Directory Project: Worms.