A Proposal for the Use of Structural Models in Physics Teaching: the Case of Friction

Formal models are insufficient for learning at school age and unsatisfactory for the student’s need to understand. We believe it important to propose structural models which can favor reasoning, interpretations and predictions, and are intellectually fruitful because they stimulate inquiry into entities and processes supposed to exist in material systems. We describe a teaching learning sequence on friction grounded on these ideas and based on a didactical reconstruction of the physics content, which has been tested in initial teacher education and with high school students. To facilitate the reproducibility of the sequence in a real school context, we have designed an open source structure, in which there is a core of contents, conceptual correlations and methodological choices with a cloud of elements that can be re-designed by teachers who can create new versions of the sequence. The teachers’ work provides a feedback useful not only to test the effectiveness of the proposal or to identify its points of weakness, but also to enrich it with new elements. The evaluation was carried out by means of a pre-test, two post-tests, work-sheets and reports written by the students, reports and comments provided by teachers and observers. Significant positive results were found. We give here some examples. The testing of the sequence with prospective teachers has provided encouraging results, from the point of view of overcoming some typical difficulties with the topic and of activating new, richer reasoning. Positive elements emerged from the comments of teachers and students, in terms of motivation, interest, challenge and feasibility. As regards the use of structural explicative models, which we consider important for understanding physical situations not merely with manipulations of formulas, the reception has been positive. The characteristics of the proposed models have been the basis for articulate qualitative explanations. The reasoning produced by the students, although incomplete, rises to a much more refined level than the simple repetition of fixed and abstract rules based on idealized objects.