The Interactive Discovery-Based Units for High-Ability Learners, for grades 6-8, provide teachers with opportunities to use exciting and challenging units in their classrooms. These engaging curriculum units culminate in authentic performance platforms that provide students with open-ended opportunities to demonstrate academic understanding. Each book in the series contains tiered lessons that teachers can easily modify to meet individual students' needs. "Ecopolis" has students run their own government to learn about issues including scarcity, resource allocation, needs vs. wants, opportunity costs, entrepreneurship, and global interdependence.