This paper explores how models can support productive thinking. For us a model is a "thing", a tool to help make sense of something. We restrict attention to specific models for whole-number multiplication, hence the wording of the title. They support evolving thinking in large measure through the ways their users redesign them. They assume new…

Through a case study of four elementary education undergraduates, we seek new analytic constructs that could help make clearer how arguments discovered or tested in quite special cases might come to support assertions that are understood to hold in general. We began analysis from a particular standpoint: to focus fundamentally on learners'…

Uses Muybridge's sequence of photos of a moving cat to examine how one might picture changes in the cat's velocity. Classroom implications include building on personally enacted physical experience and recognizing uncertainty as fundamental. Concludes that carefully examined case examples are essential in teaching students to learn and reason…

Describes the use of time-lapse photographs of a running cat as a model to investigate the concepts of function and derivative in a college calculus course. Discusses student difficulties and implications for teachers. (MKR)