Anchoring Student Reasoning in Prior Knowledge: Characteristics of Anchoring Cases in a Curriculum1

We analyze strategies for selecting and honing Anchoring Cases, which are used to elicit useful—but often implicitly held—prior knowledge possessed by most students. In an innovative model-based high school mechanics curriculum, each unit presents a Target Case, designed to elicit a persistent misconception, and an Anchoring Case. These are connected by a set of Bridging Analogies that enable the students to transfer a conception from Anchor to Target in a series of gradual steps. The curriculum has produced significant gain differences over traditional instruction on measures of understanding. This suggests the usefulness of the pedagogical strategies; however, experience has shown that it is no easy matter to create successful Anchoring Cases. We analyzed these Anchoring Cases in terms of their consistency with previously identified expert design strategies and newly identified strategies. We have organized and honed the strategies into a coherent framework (part of a much larger framework presented in Clement, 2008a), designed to help with 1) predicting which Anchoring Cases are likely to be effective; 2) developing new Anchoring Cases; 3) forming an initial theory about how and why Anchors work. These findings have implications for lesson design, teaching strategies, and pedagogical theories of conceptual change.