One of a series examining the instructional effectiveness of a videodisc-based case methodology, this study analyzed communication patterns among preservice teachers during implementation of a videodisc-based case methodology for preservice remedial reading instruction. Subjects, 12 students in an undergraduate remedial reading and practicum course, used 3 cases recorded on videodisc to explore authentic classroom and Chapter 1 situations. Hypercard technology was developed also to enhance the effectiveness of the instruction by encouraging access to multiple sources of information. Daily field notes taken during 14 class meetings were transcribed for use in a microanalysis of patterns of classroom discourse and to generate descriptions of opportunities for learning that occurred between the instructor and students. Four patterns emerged from the analysis of the discourse data: (1) the method produces active engagement and generative learning of students; (2) mediated learning has multiple textures; (3) rich contexts invite indepth analyses of information and higher-order thinking; and (4) sequenced instruction is replaced by learning that is situated in rich, complex contexts. Findings suggest that the design for using video-based cases to present authentic classroom problems can have powerful effects on preservice teachers' learning. (A list of 21 references is attached.) (RS)