Materials

• Clear plastic two-liter soda bottles (two per student team) (For consistent gathering of data, make sure all bottles used are clear plastic)
• Scissors
• Two-inch square pieces of cheesecloth, pantyhose, or handiwipes
• Rubber bands (two per student team)
• Tape
• One bag of sand or small-sized gravel
• One bag of garden soil
• Worms (100 total)
• Water
• One-cup measuring cup (one per student team)
• Organic material in separate containers: choose any three items such as grass clippings, coffee grounds, newspaper strips, pine needles, pieces of lettuce, pine needles, leaves; do not use anything that contains meat or fish
• Inorganic material: choose any one item such as plastic, Styrofoam, or fabric
• Ziploc bags (one per student team)
• Newspaper
• Sticks (coffee stirrers or pencils will do)
• Rubber gloves
• Worm journal (see assessment)

Procedure
Each student team will need two worm recycling containers. The following steps can be done prior to the first class session to save time, if needed:

1. Remove the label from the plastic soda bottle.
2. Cut the bottle into two sections; make the cut approximately one-third of the way from the bottom.
3. Cover the mouth of the bottle with a square of pantyhose, cheesecloth, or handiwipe and secure the material to the bottle using a rubber band.
4. Turn the top section of the bottle upside down and place it in the bottom section. Tape the two sections together with clear tape.
5. Place one cup of sand in the worm recycling center.

Students should complete the following tasks:

1. Ask student teams to closely observe the organic and inorganic materials in their terrarium to formulate descriptions of how they appear.
2. Students should record these observations in writing or through drawings. If a Polaroid camera is available, take a picture of each material (pictures and/or descriptions will serve as a control so that one month later students can compare what the materials look like before and after the experiment).
3. Ask student teams to predict which materials will decompose quickly and which will decompose slowly and to record their predictions.
4. Ask each student team to choose one material to study in their experiment; ensure that within the entire class at least two different types of organic materials and at least one type of inorganic material are involved in experiments . You can also assign materials to teams to ensure that an array of materials is studied.
5. Ask each student team to take one-half cup of soil and place it in a labeled Ziploc bag for future comparative study (this is a control sample so that students can compare the soil enriched in the worm recycling centers one month later to the soil sample taken at the beginning of the experiment).
6. For each of the two worm recycling centers, student teams should then place two cups of soil on top of the sand, followed by one cup of organic or inorganic material. Repeat this until the soda bottle is three-quarters of the way full. The top layer should be a layer of soil. Students should use only one type of organic or inorganic material per container.
7. Students should then add twenty worms to ONE of the containers. The other container should just contain a mixture of soil and organic or inorganic material. Cover the top of both containers with pantyhose and wrap with a rubberband. The "wormless" recycling center acts as a control to the recycling center with worms; students will be able to compare the contents of each container to determine what effect worms have on decomposition.
   *Students should add one cup of water to each recycling center and place the recycling centers where they will not be disturbed but are accessible for observation.
8. Students should observe the recycling centers once a week and record their observations in their worm journals (see assessment).
9. After students have recorded their observations, students should add one-half of a cup of water to their containers (containers need to be watered weekly).
10. At the end of one month, students should pour the contents of each container onto a separate sheet of newspaper and spread out the contents using a stick.
11. Students should walk around the room and observe the contents of each container. They should try to answer the following questions through their observations:
• How do the materials from recycling centers that contained worms compare to those that did not contain worms?
• How does each material compare to what it looked like at the beginning of the experiment?
• Which materials decomposed the most?
• Are there any materials that did not decompose at all?
• Would an earthworm be able to break down most litter if it were left in the woods?
• How is the earthworm beneficial to a wildlife community?
12. You can ask students to record observations in their worm journals individually, in student teams or as a whole class.
13. Students should return worms to a compost pile (most commercially bought worms are not capable of surviving in a garden).