This study analyzes the interpretation of diffraction and optical spectroscopy phenomena by upper secondary school students based on their use of the basic features of the wave model of light. Two teaching interventions were implemented with a sample of 60 students attending the last year of the high school curriculum, according to a subdivision into two groups: the first one (N = 34) experienced only a path about optical spectroscopy, while the second one (N = 26) experienced a path about light diffraction too. Their conceptual learning and their use of the light model was investigated through a post-test with open-ended questions. The results were compared with a similar pretest or with a control group. The responses were categorized according to an iterative method. The results show how the specific use of the wave model in the interpretation of diffraction phenomena can influence and hinder conceptual learning relating to spectroscopic phenomena. Implications for teaching are briefly discussed.
