This unit examines four topic areas related to police: rules and enforcement, police discretion, variety of police tasks, and police differences among societies as products of certain social pressures. High-school students learn about the police as an institution that responds to social and historical pressures. Students study police systems in several countries. Recognizing that these institutions vary, they begin looking at the police in terms of what a police system can be in the future. Teaching methods involving role-play, newspaper articles, and an inquiry process are employed. Thirteen learning activities are described. First, an examination of classroom rules followed by staged infractions provides insight into the relationships among rules, laws, enforcement, and discretion in enforcement. Students then experience the policeman's role directly through classroom role-play with comments from an invited officer. Comparisons of police in the United States with those of other countries include a study of British unarmed police and a discussion of the implications of Chinese marriage laws. Understanding of the structure of police forces is developed through comparisons of national and local forces in various countries and through study of a chart showing the relationship of U.S. police forces to the entire U.S. criminal justice system. (AV)