Building on research on teacher noticing, this study focused on examining how mathematics teacher educators (MTEs) can support the development of prospective teachers (PSTs’) noticing key aspects of mathematics teaching and learning through a carefully constructed video analysis activity. The authors found that the views expressed in group discussions at the beginning of the semester were not static; PSTs engaged with each other and their instructor to consider the interaction among teaching, students’ perspectives, and students’ MMKB. This finding suggests that PSTs need multiple opportunities to expose and identify their fragmented awareness and to develop more informed and considered perspectives. Discussion with peers as well as input from instructors can help PSTs move toward a greater understanding of the resources available to and used by students. This study provides some understandings of PSTs’ learning through a particular form of approximation and decomposition of practice.