A sequence of experiments and models to grasp the strange nature of light

We present a sequence of activities designed to stimulate students to reflect on the nature of light and on the different models (ray, wave, classical and quantum particles) used in teaching and learning optics. These activities are also aimed to help students in evaluating the profound meaning of the "correspondence principle" and develop their own views about some aspects of nature of science even if it is not taught explicitly. In fact, optics is a paradigmatic case where different scientific models are proposed in the University (and high school) courses. Even the oldest of these models have non empty domains of validity and both Maxwellian electromagnetism and geometrical optics are largely still used in the Physics curricula. As a consequence students are often puzzled, and think that each of these theories works in a specific domain, without any connection one with the other. Thus we investigate students' mental models of light in different contexts and we show how they develop hybrid models in explaining different phenomena or use models inconsistently.