This study examines an innovative professional development program that provides teachers with an opportunity to practice pedagogical strategies in a low stakes classroom context. Elementary teachers participated in a one-week summer Institute and two-week Practicum focused on learning strategies for facilitating scientific discourse and argumentation in their classrooms. During the Practicum, teachers taught lessons in a summer program for elementary school students and engaged in daily video-based discussions to reflect on their instruction. This study identified the instructional practices that were most emphasized during the Institute and examined the extent to which teachers took up those practices during the subsequent practicum experience. A classroom vignette illustrates how one teacher engaged her students in the discourse practices, and a coaching vignette portrays her video reflection group's discussion of the episode. Findings suggest that the focal instructional practices were taken up to different degrees during the Practicum, and that opportunities for practice and reflection are potentially valuable features of professional development programs. The project illustrates the value of video as a tool for both professional development and research.Keywords: professional development, science talk, pedagogy, science education, science instruction, classroom video DOI: 10.14712/23363177.2015.79 A growing body of empirical research on the structure, content and outcomes of effective professional development (PD) provides insights about the characteristics of programs that provide high-quality, high-impact learning opportunities for teachers. As Desimone (2009) argues, "there is a research consensus on the main features of professional development that have been associated with changes in knowledge, practice, and, to a lesser extent, student achievement" (p. 183). These features include: 1) a focus on subject matter content and how students learn that content;