This Experiment introduces students to a local ecosystem and what ecologists do: observe and describe patterns in organisms and then attempt to explain why those patterns exist. In the example used by the author, students examine tree communities found on the north and south slopes of a local mountain (in the Holyoke Range, near Amherst, MA). Student-generated questions include: Are the tree species different on the two slopes? Are there density and size differences? Are these differences due to climate and adaptation to cold and drought? Are there other important factors that help us understand the types and sizes of trees that we find there? Students collect data in groups to answer their questions.