Assessing Students' Misclassifications of Physics Concepts: An Ontological Basis for Conceptual Change

Physics novices and experts solved conceptual physics problems involving light, heat, and electric current and then explained their answers. Novices were ninth- grade students with no background in physics; experts were two postgraduates in physics and two advanced physics graduate students. Problems were multiple choice, with one correct response and three alternative responses representing possible misconceptions. For each conceptual physics problem, an isomorphic material-substance problem was constructed by imagining a materialistic conception of the physics topic and creating the resulting version of the problem. In each physics problem, one of the incorrect choices corresponded to the correct choice in the isomorphic material-substance problem. The empirical question was whether novices would reason about the physics problem as if it were conceptually similar to the substance isomorph. This question was addressed by comparing subjects' responses in the problem pairs, as well as by examining their explanations concerning all problems. A content analysis of subjects' explanations revealed that physics novices were strongly inclined to conceptualize physics concepts as material substances, whereas expert protocols revealed distinctly nonmaterialistic representations. A theory of conceptual change involving ontologically distinct categories is substantiated by these findings.