Improving comprehension in middle-grade content areas would be an easier topic to address if we had available validated theoretical models, and hence an understanding, of 1) how one learns from text, and 2) how intellectual operations develop in adolescence. Our current state of ignorance in these areas has been aptly summarized by Miller (1976) and Neimark (1975) respectively. We are then, like everyone else who would discuss improving comprehension of text, reduced to drawing upon the available body of literature and from this attempting to produce a framework from which useful strategies can be developed.
Allington, R. L., & Strange, M. (1979). Remembering is Not Necessarily Understanding in Content Areas. Reading Horizons, 20 (1). Retrieved from http://scholarworks.wmich.edu/reading_horizons/vol20/iss1/11