For kids with an interest in science, compost is a fun way to show how leaves and other litter on the forest floor become nutrients that feed trees. Kids can help create a compost heap by assisting with gathering materials such as leaves and grass clippings, or even collecting kitchen scraps including coffee grounds and leftover vegetable peels and similar items from neighbors and retail outlets like coffee houses and fruit stands.
Create a compost bin by bending chicken wire into a circle that is at least 3 feet in diameter and 3 feet in height.
Sort compost scraps into two classifications, browns and greens. Explain that browns are dead, dried plant parts including pine needles wood chips, straw and fallen leaves. Browns are filled with the element carbon. Greens are fresh, alive plant parts such as lettuce leaves and grass clippings. Greens are full of the element nitrogen.
Pile the compost into the chicken wire bin in layers like lasagna. Each green layer should be half as thick as the brown layers.
Wet the compost so that it remains only as damp as a wrung-out sponge. Explain that the wet compost creates an environment for tiny microbes to eat the scraps. As the microbes eat the scraps, they turn them into the spongy dirt-like substance we call compost.
Let kids test the middle of the soil with a cooking thermometer to determine the internal temperature. Explain that the tiny microbes eat the most compost when the internal temperature is between 120 and 150 degrees and that if the temperatures rise over 160 degrees, it will kill the microbes. Let them know that every time you turn the compost, it raises the temperature. Put the kids in charge of deciding when you will turn the compost.
Sift through the compost when it is nearly all the consistency of dirt. Pick out any large pieces of undigested compost scraps and return them to the compost pile to start a new compost heap.