This manual describes the model--specifically the observation procedures and coding systems--used in a longitudinal study of how children learn to comprehend what they read, with particular emphasis on science texts. Included are procedures for the following: identifying students; observing--recording observations and diagraming the room; writing transcripts--noting instructional and noninstructional utterances, and reporting other than whole-class instruction; updating, coding, and storing rosters; preparing coding sheets; and assuring reliability. Codes and categories describing the following are defined: group and individual student-teacher interactions--frequency of group meetings and combined groups; noninstructional time--teacher directed instruction, including all other subject areas, adult reading, teacher assigned centers, and testing; teacher-initiated instructional interactions (questions and statements) regarding vocabulary, sequencing, paragraph comprehension, spelling, grammar, or repetition of a word; and teacher feedback--praising, ignoring, or requiring homework. Also included are examples of transcripts, coding sheets, references, and graphic presentations of the model. (LLZ)