Preservice teachers have pre-existing conceptions of teaching that develop throughout many years of being students in the presence of teachers. Teacher educators are faced with the challenge of making the invisible parts of being a teacher visible to their students. This paper presents some of the activities, especially related to videotaped case studies, that were found to be effective in helping preservice science teachers recognize the diversity in their classrooms and the effort that it takes to meet the needs of all students. (Contains 36 references.) (WRM)