Tragedy of the Commons is the mind set: "If I don't use the resources then someone else will." This is a simulation that allows students to explore how the common usage of a potentially renewable resource can lead to its exploitation. Students will complete an activity, a data sheet, an analysis of the data, and a comparison of this problem to a local environmental issue. Students will pose solutions to this problem.This lesson plan was created as a result of the Girls Engaged in Math and Science, GEMS Project, funded by the Malone Family Foundation.