Noting that successful comprehension, problem solving, and decision making are dependent upon activation and appropriate application of relevant schemata of existing knowledge, this report examines the practice of oversimplifying information in the content areas to make teaching and studying easier, and the dangers inherent in doing so. The report first develops principle contentions concerning well-structured domains of knowledge (WSDs) and ill-structured domains (ISDs). Schema theoretic knowledge representation and the problem of transfer and related research are also examined. The report then examines the practice of overgeneralizing in teaching, focusing on (1) ill-structuredness of some content; (2) the use of case study; (3) the nonlinear and multidimensional arrangement of cases; (4) empirical dimensions for testing the theory (including results of a study of curriculum simplification); (5) suggestions to bring about a science of instructional sequencing, case selection, and case arrangement; (6) the role of visual-perceptual representations and adjunct aids in transfer; and (7) discovery learning in a well-structured domain. Concluding remarks suggest that the learning principles proposed in the report will make ill-structured material easier to teach and understandable for students. (Three pages of references and one page of footnotes are included.) (JC)