Decomposition is a natural process to eliminate organic waste left by plants and animals. Bacteria and other creatures known as decomposers break down leaves, grass, food scraps and sticks to make a nutrient rich additive for soil. Compost is an inexpensive alternative to buying fertilizers and prevents yard waste from going to a landfill. Yard and food waste makes up 13% of household waste that is thrown away in the United States.

Composting Classroom Activities

PreK-3: CSI: Compost Science Investigation

Grades 3-6: Decomposition

Objective: Students will compost organic material and observe how materials decompose.
Materials: Compost materials: leaves, vegetable, fruit, bread, plant clippings, hay, straw, strips of newspaper, sawdust, pine needles; Composting container: clear heavy large plastic bag, zip lock baggie, or clear plastic 2-Litter bottle or glass jar; 5 gallon bucket; Natural activator: garden soil, compost, manure, alfalfa meal, cottonseed meal; Scoop: garden shovel, spoon
Vocabulary: compost, decomposition, organic matter

Procedures:
Students can compost as a class experiment or in teams.

1. Students collect food waste from home or from their lunches. No oil, dairy, meats or salad dressing.
2. Create mixture by mixing all materials in a large bucket unless you plan to test materials separately. Add 2 parts brown (leaves, hay, straw, newspaper or sawdust), 1 parts green (vegetable, fruit, bread, plant clippings or pine needles), and 1 part activator. Fill container three-fourth full with compost mixture. Sprinkle water to make moist, if needed. Seal the container or bag and knead or shake. Keep container in a warm place. As an alternative experiment, added water to the compost and leave other dry; aerate compost by allowing oxygen in the container and leave the other sealed without air.
3. Allow air into compost and mix it every few days.
4. Students should record observations once a week for 6 to 8 weeks on changes in composition of the compost mixture and color of compost.

Conclusion:

• Review changes of the compost materials throughout the experiment.

Time: one class period for prep, long term observations.

Extenstion: Use a mixture of soil and compost to plant seeds.

Grades 7-12 ISW: Comparative Composting

Click here to learn about comparative composting.

Web Resources:

www.wormwoman.com: Vermicomposting
http://www.oldgrowth.org/compost: Compost resource page
www.compostingcouncil.org: Composting Council
http://www.a-horizon.com/compost/compost_menu.html: Rot Web
http://go4green.sask.com/home/garden/compost5.html: Go For Green
http://compost www.css.cornell.edu/composting_homepage.html: Cornell Composting