Recent research has focused on how prospective teachers formulate beliefs related to teaching and learning mathematics and science. This paper examines the use of videotaped mathematics and science lesson segments to aid in the description or identification of initial belief structures of prospective elementary school teachers. Using a naturalistic approach, written comments about three videotaped lesson segments were collected from 38 college students in a mathematics education content course. The videotaped lesson segments were interpreted and edited to present the prospective teachers with predetermined aspects of teaching. The three segments included a first-grade subtraction lesson, a fifth-grade math/science integrated lesson, and a second-grade constructivist mathematics lesson. Students' comments were categorized by lesson segment and analyzed across lesson-groups for commonalities and differences. Results indicate that the prospective teachers already had various preconceptions intact regarding issues of both teaching and learning before they entered the content class. Specific preconceptions are reported by lesson segment. Possible implications from the findings include: (1) the use of videotaped lessons is an effective way to identify prospective teachers' existing beliefs; (2) teacher educators cannot assume that prospective teachers' prior experiences are in conflict with teacher education objectives; and (3) consideration of these beliefs provides an opportunity for teacher educators to target those beliefs and for the prospective teachers to have an active role in their education experiences. Contains 28 references. (MDH)