Teachers’ knowledge of proportional reasoning is important, particularly in the middle grades in the USA. This exploratory study investigated 32 teachers’ use of knowledge resources in two mathematically similar tasks (one a paper and pencil task, the other a dynamic task) around proportional reasoning. The two tasks invoked different knowledge resources by the same teachers. Results suggest questions to the field around how we access or invoke teacher knowledge and the need to more purposefully explore the potential benefits of using a dynamic task to invoke knowledge resources.
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