The investigation described here is intended for a 9th-10th-grade biology class, and should take about two weeks. Students may be especially interested in the cycling of carbon since it is a source of energy, has an impact on climate, and is part of all living things. Many materials cycle through Earth's systems, providing a wide range of opportunities for students to investigate these processes and build their understanding of the cycling of matter. In both middle school and high school, students are expected to develop and use models that describe the cycling of energy and matter within the Earth and between the Earth and its ecosystems.

Reuse: This item is offered under a Creative Commons Attribution-NonCommercial-ShareAlike license You may reuse this item for non-commercial purposes as long as you provide attribution and offer any derivative works under a similar license. Provenance: Anne Egger, Central Washington University