RR 89-5 Thinking about teaching subtraction with regrouping: A comparison of beginning and experienced teachers' responses to textbooks.
This paper reports a comparative analysis of beginning and experienced teachers' thinking about teaching subtraction with regrouping and the role that textbooks play in their deliberations. The teachers were asked to compare and appraise two contrasting textbook selections dealing with this topic and to describe how they would teach it. The analysis revealed both differences and similarities between the experienced and beginning teachers. Not surprisingly, experienced teachers had more elaborated lenses for looking at the textbooks and thinking about how to teach the topic. While both experienced and beginning teachers seemed to assume that manipulative materials were inherently worthwhile, neither beginning nor experienced teachers discriminated among particular concrete materials and all seemed to think that seeing or touching such materials automatically produces understanding. Nor did the two groups differ significantly in their understandings of multidigit subtraction. This finding challenges the common belief that teachers learn about their subjects by teaching them and suggests an important role for textbooks in developing teachers' understandings of the appropriate use of concrete materials.