This study compared conversations among groups of teachers of high school geometry that had been elicited by a representation of instruction (either a video or an animation) and facilitated with an open-ended agenda. All artifacts used represented instruction scenarios that departed from what, according to prior work, had been hypothesized as…

This article focuses on an experienced high school mathematics teacher who changed her practice without participating in planned interventions aimed at producing this change. It reports on the nature of the teacher's change from her perspective and an interpretation and understanding of the change from the researcher's perspective. It illustrates…