Photographs offer teachers a way to collect and explore student work that might other wise go unnoticed or minimally examined. A teacher might use photographs to analyze students' strategies and work to promote future instructional practices that result in higher student achievement. As a tool, photographs document student understanding and…

Eliciting, responding to, and advancing students' mathematical thinking all lie at the heart of great teaching. In this article, the authors describe a formative assessment approach that teachers can use to learn more about their students' mathematical thinking and inform their instructional decisions. This assessment approach draws on a widely…