Naive physics reasoning: A commitment to substance-based conceptions

A good deal of research has addressed the topic of naive physics knowledge, with a focus on the physics domain of classical mechanics. In particular, it has been proposed that novices enter into instruction with an existing, well-defined knowledge base that they have derived from their everyday experiences. Most relevant initial knowledge will be substance based, in the sense that it represents the novice's understanding of how material objects and other types of substances behave in the course of everyday life. Our position is that novices make every effort to assimilate new physics knowledge into their initial knowledge structures. Thus, abstract physics concepts will tend to be attributed with properties or behaviors of material substances. For example, force is considered by many novices to be a property of moving objects. Novices also appear to draw on their substance knowledge when they are asked to reason about other abstract concepts, such as light, heat, and electricity. Many researchers have explored naive conceptions of these concepts to the extent that a fairly broad view of the literature is now accessible. This article opens with a discussion of naive knowledge of material substances (including objects) and presents a broad theoretical framework called the substance schema, which is used throughout the article to refer to any generalized knowledge of material substances and objects. It must be noted that the term schema is used loosely in reference to any existing generalized knowledge; no arguments are presented concerning the actual "structure" of conceptual knowledge. Misconceptions of the concept of force are first briefly reviewed, followed by more extensive reviews of research concerned with naive conceptions of light, heat, and electricity. These reviews provide support for the claim that naive conceptions often reflect an underlying commitment to existing knowledge of material substances. The article closes with a discussion of the use of materialistic models by physicists and implications for instruction.