Abstract
This study investigates the ways in which knowledge changes were and were not congruent with the conceptual change model of instruction, when astronomy students were taught according to that model.
One leading conceptual change model has been suggested by Posner et al (1982). Their model recommends that
instruction create dissatisfaction with students' existing incorrect models, provide alternate models that are intelligible and plausible, and allow students to experience the fruitfulness of their models by explaining and predicting observations.
Students were instructed about the phases of the moon according to this prescription. Tests covering the phases were given before, during, and after instruction. A coding scheme was used to interpret the test responses so as to characterize students' models. The coded data were then used to portray changes, that took place during instruction, using definitions of accommodation and assimilation derived from conceptual change theory.
Eight of the nine students starting instruction with alternative models did not sustain those alternative models throughout instruction. These results, consistent with expectations of the Posner et al model, suggest that this method has promise, especially in cases where students enter instruction with alternative models.
Students who did not begin instruction with alternative models made significant gains. These results suggest that this method will help such students assimilate correct propositions.
One third of the students in this study developed alternative models as a result of the first phase of instruction, in which students made observations of the moon. Eighty-three percent of these students did not sustain these alternative models throughout instruction, suggesting that the Posner et al method can be used to address misconceptions that arise during instruction.
Finally, the changes described as accommodation were not wholesale changes. They are better described as piecemeal deletions and additions of key propositions that occurred against a base of stable propositions. Those teaching to create accommodation should aim to change the incorrect propositions while building new knowledge upon the pre-existing base of correct knowledge.
