LEARNING MATHEMATICS FOR TEACHING

to questions about how to promote and assess it. What kinds of professional development experiences might provide teachers with the opportunity to develop mathematical knowledge for teaching? What does it mean to learn it? In this paper, we address these questions with illustrations of teachers learning various aspects of mathematical knowledge for teaching. These teachers were participants in Turning to the Evidence1, a study investigating the role of practice-based professional development centered in the use of classroom artifacts (e.g., student work and classroom video) and its effect on teacher learning2. MATHEMATICAL KNOWLEDGE FOR TEACHING Mathematical knowledge for teaching focuses attention on the considerable mathematical demands that are placed on classroom teachers (Ball & Bass, 2000; Ball, Bass, & Hill, 2004). Building on Shulman’s (1986) notion of pedagogical content knowledge, characterized as “bundled ” mathematical, pedagogical, and cognitive/developmental knowledge which can help teachers anticipate and address typical issues of students ’ learning mathematics, Ball and Bass posit an “unbundled,