THE ROLE OF HYPOTHETICO-DEDUCTIVE REASONING AND PHYSICAL ANALOGS OF MOLECULAR-INTERACTIONS IN CONCEPTUAL CHANGE

Two hypotheses about theoretical concept acquisition. application, and change were tested. College biology students classified as intuitive, transitional, or reflective (hypothetico-deductive) reasoners were fi rst taught two theoretical concepts (molecular polarity and bonding) t o explain the mixing of dye with water, but not with oil, when all thr ee were shaken in a container. The students were then tested in a cont ext in which they misapplied the concepts in an attempt to explain the gradual spread of blue dye in standing water. Next students were taug ht another theoretical concept (diffusion), with and without the use o f physical analogues. They were retested to see which students acquire d the concept of diffusion and which students changed from use of the incorrect polarity and bonding concepts (i.e., the misconceptions) to use of the diffusion concept to correctly explain the dye's gradual sp read. As predicted, the experimental/analogy group scored significantl y higher than the control group on a posttest question that required t he definition of diffusion. Also as predicted, hypothetico-deductive r easoning skill was significantly related to correct application of the diffusion concept and to a change from the misapplication of the pola rity and bonding concepts to the correct application of the diffusion concept to explain the gradual spread of the blue dye. Thus, the resul ts support the hypotheses that physical analogues are helpful in theor etical concept acquisition and that hypothetico-deductive reasoning is needed for successful concept application and change. Educational imp lications are drawn.