This exercise, designed for use by upper elementary and high school students, introduces the concepts of model and system. By examining a physical model, such as a top, the student learns the concepts of model and system which can later be applied to the study of social systems. A large system of interrelated parts is examined and the system and sub-systems analyzed. Emphasis is upon the concept formation of interdependence. Understanding of the two concepts is viewed as a prerequisite to the study of world politics in which there exists an interdependence among all nations. Objectives, a list of needed materials, and procedures are briefly stated. Sixteen questions for examination of the model are included to help students define the two concepts; analyze advantages and disadvantages for studying systems; represent a system pictorially, orally, or in writing; and recognize essential and non-essential parts and sub-systems. (Author/SJM)