This study investigated how graduate physics teaching assistants (TAs) develop professional knowledge for teaching the undergraduate introductory physics curriculum, Matter and Interactions (M&I). M&I is a physics course that focuses on the application of a small number of fundamental physical principles on the atomic and molecular nature of matter. In this study, the author examined the process of five TAs' development of knowledge for implementing the M&I course--from the time they engaged in an M&I content and methods workshop through their first semester as TAs for the course. Through a qualitative, multiple case study research design, data was collected from non-participant observations, digitally recorded video, semi-structured interviews, TAs' written reflections, and field notes and analyzed using the constant comparative method.

The TAs' knowledge for teaching M&I was identified in three domains: pedagogical content knowledge, pedagogical knowledge, and subject matter knowledge. First, the three components of TAs' pedagogical content knowledge were identified. Second, pedagogical knowledge that the TAs demonstrated during the study fell predominantly into the category of classroom management and organization. The knowledge of classroom management and organization was categorized into two components: time management skills and group composition. Last, the TAs' subject matter knowledge developed through their M&I teaching experience was described in terms of the M&I curriculum conceptual structure, the new approach of the M&I curriculum, and specific topic knowledge.

The TAs' knowledge for teaching developed from propositional knowledge to personal practical knowledge, and the process of knowledge development consisted of three phases: accepting, actualizing, and internalizing. In addition, the TAs' knowledge developed by combining various components of knowledge for teaching.