Theoretical frameworks are useful to developmental educators investigating the areas of grammar, critical reading, and the introductory physical science course. Of all available approaches to grammar, sector analysis proves the most powerful as a tool for developmental educators. It is designed to show how a few possible grammatical constructions, appearing within various sectors, shape the meaning of the sentence as a whole. As a tool for describing the varieties of constructions in various positions, it offers a precise diagnosis of student writing, in terms of both strengths and weaknesses. As for critical reading, a model based on recognition of patterns of content, language usage, and rhetorical devices--and their interaction--provides for diagnosis of students' abilities with such subskills as classification, pattern recognition, and inference. When teaching science, teachers must assure not only that developmental students perceive scientific phenomena in terms of the fundamental perceptual categories, but also that they are familiar with the "grammar" by which the measurements of those properties are interrelated in the derivation of more sophisticated concepts/properties. With such theoretical approaches, developmental educators can focus on specific materials and student behaviors within the various disciplines. Handouts illustrating points discussed are included. (HOD)