This paper describes a case study of the use of cases in teacher education, comparing the responses of three prospective teachers to three cases of teaching. In an introduction to teaching course, the teacher educator used the three cases to provide alternative images of practice, hoping to influence the students' beliefs about teaching and about learning to teach. The students analyzed three videotapes, each of which was paired with a single article and presented as response to a central question about teaching. The findings were based on: interviews with the students at the beginning and end of the course; an essay on teaching which the students were required to write, and analysis of four written conversations assigned in the course. Students' entering beliefs about teaching remained central in their interpretations of the cases throughout the term, although each prospective teacher learned new ideas about teaching that were compatible with her initial beliefs. Implications are discussed for the use of cases in teacher education for purposes of challenging and extending prospective teachers beliefs. (Contains 32 references.) (ND)