Decayed plant materials mixed with other organic matter creates compost. Observing a compost bin or pile can demonstrate biodegradation over time. Encouraging kids to collect food scraps and yard refuse, such as grass clippings and leaves, and mixing them with light soil can teach children what materials are organic. Kids can watch over time as the compost pile turns from a heap of trash into dark rich soil, visually witnessing the process of biodegradation.
The National Institute of Environmental Health Sciences installed what the agency calls "Worm Wigwams" that convert organic waste into usable materials. According to the NIEH, this process requires a fraction of the time that regular composting takes. Using a compost bin with insulated walls, heating the interior to maintain a steady temperature, and depositing red worms into the organic materials, facilitates the breakdown of organic materials into mulch. According to the NIEH, the worms digest different types of material including vegetable waste, chopped plant materials and shredded paper products. The vermicompost is the castings from the red worms after processing the waste. This material is said to be a superior potting soil.
With the help of knowledgeable adults, a miniature version of a vermicomposting operation can be constructed in a classroom or at home. Add a variety of organic materials to the bin, along with red worms. Shredded paper and cardboard, coffee grounds, vegetable matter such as kitchen scraps, plant materials such as leaves and grass clippings and loose soil can all be added to the bin. Regular turning of the refuse, at least twice a month will help the process along.
Demonstrating the reusable value of byproducts created from the breakdown of biodegradable materials can be accomplished in a small vegetable garden or with potted plants. The children can grow four or more identical plants, half in soil enriched with decomposed plant materials and half in ordinary soil to observe the results of having extra nutrients deposited in the soil through biodegradation.
Depending on the environmental conditions and the contents of the bins, it may take six months for the compost to mature to the point of being usable for planting. An ongoing project, demonstrating the process of biodegradation through composting and subsequently using the finished product for potting soil, cannot only teach kids about biodegradation, but the benefits of recycling ordinary household refuse. [Ref 1, 3]