This inquiry focuses on understanding the carbon cycle and its impact on the global environment and economy. After learning about the original carbon cycle, students will examine how humans have changed the system, and what impact our involvement in the system has on the environment. Using the city of Freiburg, Germany, as a sustainability model, students will research other communities and their sustainability efforts. Students will use the sustainabiity business model of Siemens as a case study as they learn about Germany's energy plan, Energiewende, and then research other companies' sustainability efforts. Finally, students will determine their own carbon footprint and ways they can reduce it. Teachers may wish to provide students with an example of certain handouts instead of printing copies thus highlighting how to reduce carbon emissions by reducing paper.