The purpose of this resource is to help students articulate and integrate their existing knowledge about the air, water, soil, and living things by viewing them as interacting parts of a system. Students visit a study site, where they observe and recall their existing knowledge of air, water, soil, and living things to make a list of interconnections among the four Earth system components. They make predictions about the effects of a change in a system, inferring ways these changes affect the characteristics of other related components. Educational levels: Middle school, High school