Instructional explanations as an interface-the role of explanatory primitives.

What makes an instructional sequence in physics meaningful to students? Why do some explanations seem more plausible than others? Why is it that an explanation can appear plausible to one student but not to another? We present a model that addresses these questions. Elaborating diSessa's (1993) concept of p-prims, we develop a model of explanatory primitives and argue that different individuals have different sets of explanatory primitives, or they assign different priorities to the same explanatory primitives. Individual differences in explanatory primitives can account for differences in reactions to an instructional explanation, and we present empirical data to support this claim. We then use the model to analyze Jim Minsrell's (1982) instructional sequence about normal forces to illustrate how an effective learning sequence addresses differences between individuals by evoking a rich set of explanatory primitives. [ABSTRACT FROM AUTHOR]