The lessons in this 3-part series are intended to provide students with a basic understanding of the relationship between the United States and Mexico, with emphasis on multiple perspectives, conflict and cooperation, and interdependence. This curriculum unit, Part 3, examines the economic interdependence of the United States and Mexico to learn how events and changes in Mexico affect and continue to impact the economy, society, and politics of the United States. The introduction presents a rationale, state and national history standards, series goals, matrix of lessons, materials needed, time and suggested sequence of activities, and small-group roles. This unit contains four lessons: (1) "Setting the Context for U.S.-Mexico Relations" (contains handouts and maps); (2)"Categories of Trade: The U.S.-Mexico Case" (contains a fact sheet); (3) "Interdependence and Devaluation: A Case Study" (contains handouts and teacher material); and (4) "Twin Cities Working Together: A Case Study" (contains 7 position papers, teacher material, and a transparency). (BT)