Studies related to teacher training in primary education indicate a lack of knowledge, low levels of teaching self-efficacy, and negative emotions towards the teaching of physics. The main objective of this research was to compare the influence of two teaching methodologies on the learning and teaching self-efficacy of teachers-in-training on optics content related to light and color. The research design was quasi-experimental with control and experimental groups, a pre-test, and two post-tests. A non-probabilistic sample of 173 trainee primary school teachers was used. The control group used an academic--expositional teaching methodology, and the experimental group used a practical methodology based on the use of STEM teaching tools. Measuring instruments were designed and applied before and after the interventions to measure the evolution of cognitive and competence variables of the participating sample, depending on the methodology applied, both in the short and long term. The results reveal statistically significant improvements between the control group and the experimental group, both in the knowledge level variable and in the teaching self-efficacy variable.