"Lesson purpose" in its social and cultural context: video ethnographic evidence on the functioning of a highly rated curriculum unit in diverse middle school science classrooms

This paper explores the use of video ethnographic data as a source of evidence for documenting how, and whether, "lesson purpose" is conveyed in highly rated science curriculum units. Although its importance is widely assumed by evaluators of instructional materials and practices (e.g. Project 2061), its social and cultural functions in demographically diverse classrooms are not well understood. Based on more than 2,500 pages of transcription and 120 hours of digital video from two different classrooms over the course of two years, this study examines "lesson purpose" as an interpretive act carried out by students and teachers collaboratively through processes of clarification, object manipulation and scientific term use. By demonstrating variations among students and between classrooms, the study outlines the features of a classroom ecology by which "lesson purpose" functions.