The purpose of this paper is to outline elements that are critical for an effective analysis and revision of instructional units of a learning system. No attempt is made to present an exhaustive list of critical elements nor a list of elements that are necessarily mutually exclusive. The elements that are presented in the paper, although consisting of a first approximation, appear to subsume characteristics that account for most of the ineffectiveness of instructional systems. They are the distillation of extensive experience in the analysis and revision of an actual individualized, performance-based instructional system that constituted the entire teacher education program of a School of Education. Examples to illustrate the categories will be drawn from actual practice. (Author)