Professional development programs today increasingly ask teachers to capture video in their own classrooms to share with peers. Yet little work has explored the nature of the videos that teachers produce for this purpose. This study takes a first step by looking inside a set of almost 200 videos collected by 84 K-2 teachers participating in one of…

This study explores the use of video clips from teachers' own classrooms as a resource for investigating student mathematical thinking. Three dimensions for characterizing video clips of student mathematical thinking are introduced: the extent to which a clip provides "windows" into student thinking, the "depth" of thinking…

Video is currently a key element of numerous professional development programs, yet relatively little is known about how video fosters changes in teachers' thinking. This study examines how a particular type of video-based professional development, namely video clubs, supports teacher development. Video clubs are professional development…