Using video clips of mathematics classroom instruction as item prompts to measure teachers' knowledge of teaching mathematics

Responding to the scarcity of suitable measures of teacher knowledge, this article reports on a novel assessment approach to measuring teacher knowledge of teaching mathematics. The new approach uses teachers' ability to analyze teaching as a proxy for their teaching knowledge. Video clips of classroom instruction, which respondents were asked to analyze in writing, were used as item prompts. Teacher responses were scored along four dimensions: mathematical content, student thinking, alternative teaching strategies, and overall quality of interpretation. A prototype assessment was developed and its reliability and validity were examined. Respondents' scores were found to be reliable. Positive, moderate correlations between teachers' scores on the video-analysis assessment, a criterion measure of mathematical content knowledge for teaching, and expert ratings provide initial evidence for the criterion-related validity of the video-analysis assessment. Results suggest that teachers' ability to analyze teaching might be reflective of their teaching knowledge.