This study examined the text organization and structure of fourth and sixth grade science textbooks. This included prereading questions, advance organizers, margin notes, and type of text structure. In addition, chapter activities were classified as to the degree of problem solving skills developed by ranking the activities according to Bloom's (1956) taxonomy of cognitive skills.
Farris, P. J., Kissinger, R. W., & Thompson, T. (1988). Text Organiztion and Structure in Science Textbooks. Reading Horizons, 28 (2). Retrieved from http://scholarworks.wmich.edu/reading_horizons/vol28/iss2/6