Six high school student teachers were video-taped during the first, seventh and fourteenth weeks of their sixteen-week teaching semester. Pupils in these classes evaluated the personal characteristics and instructional behaviors of their student teachers using the Classroom Teacher Inventory. Resulting data suggested that the original sample of student teachers included two who were perceived by pupils as most effective and two who were perceived as least effective. The remaining data analysis focused on similarities and differences between the most and least effective student teachers. Most effective student teachers were perceived by their pupils as being nonpunitive, consistent and predictable. Instructionally, the most effective student teachers were perceived by their pupils as showing enthusiasm, asking interesting questions, accomplishing goals, and being very clear in their teaching. Stimulated recall analysis of the video tapes suggested differences in the management of transitions between lesson segments. The most effective student teachers averaged fewer transitions per lesson, used less time for transitions, and experienced fewer behavioral problems during transitions. Also, the most effective student teachers used a much smaller proportion of the total lesson time for transitions than did the least effective student teachers. (JD)