This study analyses an online scenario-based instrument in which secondary mathematics teachers from across the United States were presented with episodes of mathematics instruction and then asked to make a decision at a critical juncture. The theory of practical rationality suggests that the decisions of mathematics teachers can be understood as…

A historical review of mathematics textbooks suggests a canonical method to solving equations that teachers often see as "the" way to solve equations. In this paper, we examine data from a nationally-distributed sample of 524 secondary mathematics teachers who responded to scenario-based survey items that represent the instructional…

We describe the development of measures of teachers' recognition of an instructional norm--that proof problems in high school geometry are presented in a diagrammatic register. A first instrument required participants to openly respond to depictions of classroom scenarios in which the norm was breached. A second instrument was a survey that…

Background/Context: For decades, teacher educators and professional developers have been using video recordings of actual classroom practice to help teachers reflect on their teaching (e.g., van Es & Sherin, 2002, 2008) and to help preservice teachers come into contact with practice (Lampert & Ball, 1998). However, the use of video records of…