Interaction between radiation and matter: a proposal to link optical and thermal properties in the upper secondary school curriculum

The work we present aims at bridging two areas, optics and thermal phenomena, strictly connected from a conceptual, scientific and technological point of view, but often taught separately (with episodic connections) in high school. We elaborated a teaching learning sequence (TLS) on the thermal effects of interaction between radiation and matter, infrared emission of bodies and greenhouse effect. The research is based on a “three-dimensional approach” to the design of research-based TLSs, which involves a synergic integration of three aspects: a critical analysis of the scientific content in view of its reconstruction for teaching, an overview of current proposals (textbooks, common teaching), and an analysis of didactic research on the topic. While research has been carried out on pupils’ conceptions about the greenhouse effect and global warming, specific studies and teaching proposals for secondary school about radiation–matter interaction are still lacking. Our research focuses on these aspects. For example, we have frequently found a confusion (also in textbooks) between transitory phases in which temperature changes and steady state situations, a tendency to give absolute meaning to optical properties (transparency, absorptivity, emissivity) as intrinsic characteristics of bodies, a lacking or incorrect consideration of IR emission in thermal balances, a difficulty in taking into account the systemic interdependence of all factors and phenomena implied in energy balances. The sequence stresses the dependence of the optical properties of materials on radiation frequency and the complexity of this dependence, as result of interaction between matter and radiation. Multiple experiences are proposed to favour a progressive construction of knowledge, from the simplest through the more complexes cases, in a dialectic relation between hypothesis, experiments, refined or unexpected observations and more complex explanatory frameworks. The results of the experimentation with future teachers and pupils will be presented. Part of the work is carried out within “OutLab” Comenius Project.