Compost bins are beginning to make their way into home gardens and classrooms, allowing students to actively participate in greening their environment. However, do they really understand the process of composting? According to the "National Science Education Standards" (National Research Council [NRC] 1996, 20), "Learning science is something students do, not something that is done to them." Through the use of a microcomposter, students can study the composting process in their classroom and see the rich diversity of organisms present in the compost they create. This compost and the organisms in it can be considered a mini-ecosystem. Students can observe and test factors that affect the decomposition of organic matter and the recycling of these elements into the ecosystem. This article describes activities that teachers can do with students to assist them in understanding the composting process and exploring the biodiversity that can be found in leaf litter and compost. (Contains 1 note and 9 figures.)