This Technical Paper focuses on principles for teaching problem solving. Part 1 addresses the need to teach problem solving. Part 2 defines problem solving skills, and describes: general problem solving models of the 1960s and 1970s, current problem solving models, declarative knowledge, mental models, expert versus novice knowledge, procedural knowledge, and near and far transfer. A table provides a definition, characteristics, examples, and implications for teaching and testing for three problem types: well structured problems, moderately structured problems, and ill structured problems. Part 3 provides a summary of 17 principles that form the basis of problem solving instruction in the PLATO[R] system. (Contains 30 references.) (AEF)