This book and its companion volume include narratives by teachers who are working with constructivist methods and principles to transform their practice along the lines mandated by the National Council of Teachers of Mathematics Standards. In this volume, nine teachers describe their struggle to understand constructivism and its application to learning mathematics, and transform their mathematics instruction. These teacher narratives are complemented by four essays written by teacher educators which explore some of the challenges posted by the new mathematics pedagogy for the multiple identities teachers are being asked to enact as mathematical thinkers, managers of classroom processes, monitors of student learning, and as members of the wider mathematics education community. (MKR)