Humans can have a big impact on the environment, specifically the influence they have on the carbon cycle. First, the class will define and discuss each of the earths four major spheres, the biosphere, hydrosphere, atmosphere, and lithosphere. Then, they will turn their attention to the carbon cycle as it is influenced by human choices and how human choice interacts within each of the four spheres. The lesson culminates as the class creates informational posters describing the cycle, ways humans negatively impact the carbon cycle, and ways they can improve it.