ABSTRACT
We describe the mechanism for teacher learning as the evolution of pedagogical judgment, the interplay between pedagogical action, pedagogical reasoning, and pedagogical responsibility. Pedagogical action refers to what teachers do in their role; pedagogical reasoning refers to their reasons for and interpretations of those actions; and pedagogical responsibility describes their institutional, legal, and ethical commitments and obligations. By distinguishing a normative view of telos (what teachers learn) from a general mechanism (how learning happens), this description accounts for a wide range of teachers' concept development, including learning that would not conform to the vision of ambitious and equitable mathematics teaching. Drawing on Vygotsky, we emphasize how the dialectic between lived concepts, which are often pedagogical actions, and scientific concepts, the narratives of pedagogical reasoning and responsibilities, accounts for teachers' changing understandings of practice.
