The progressive agenda of science education reform, particularly the goal of promoting student inquiry, places substantial intellectual demands on teachers. If this reform is to succeed, the education community must do more to appreciate and address its demands. This paper presents three examples of high school physics teachers' conversations about "snippets" of each others' work with students. The purposes are: (1) to highlight the central role and intellectual demands of teacher inquiry, in particular teachers' diagnoses of students' strengths and needs; (2) to suggest that teachers often experience and express their diagnoses in terms of instructional strategies; and (3) to suggest that the value of educational research for instruction be understood primarily with respect to what it may contribute to teacher inquiry. (Contains 15 references.) (Author/ASK)