The essentials of Piaget's theory and its application to teaching at the college level are described as part of the Learning and Evaluation Service workshop, Teaching Students to Reason, offered at Michigan State University. Objectives are to enable the teacher to: (1) diagnose and classify reasoning patterns of students; (2) evaluate current instructional materials and techniques in light of Piaget's theories; (3) redesign instruction to incorporate Piagetian concepts in order to facilitate the type of reasoning appropriate for the course; and (4) use guidelines for designing tools to evaluate reasoning skills. Examples are presented from various subject matters to enable the teacher to understand how many of the principles can be applied to college courses. After close examination of concrete and formal operation, a list of characteristics associated with each level of reasoning are presented, as are examples of student responses that can be classified accordingly. Some general teaching strategies that are useful to promote reasoning abilities in learning are presented for the following areas: when introducing a new topic, during instruction, when using the laboratory, when making assignments, and when testing. (SW)