For individuals to cooperate they must develop certain skills and understandings. Unless schools engage in specific activities that teach cooperation, students may lack the skills they need to function in an adult society. Cooperative learning has much to offer for the mathematics class. Students enjoy discussing mathematics with other students. They benefit from their interaction with peers as well as with the teacher. This booklet provides a rationale, examples and discussions of methods designed to help teachers add cooperative learning to their repertoire of instructional methods. Homework reviews, lesson planning, group formation, features of successful groups, and the teacher's role are described. Twenty problems designed to be solved in cooperative-learning groups of students are provided with instructions, and student hand-outs. (CW)