In this work we present our content-research studies aimed at identifying conceptual learning pathways in physics for students of different ages and for teacher education in the 30 years of research of the Udine Physics Education Research Unit (UPERU). They are based on the Model of Educational Reconstruction (MER) revisited by focusing on disciplinary fundamental concepts of the selected topic, aiming at conceptual change with respect to the knots that differentiate common sense from scientific ideas. Learning trajectories are sought in the pathways, with tools, strategies and methods studied for the purpose. The research involves analysis of learning processes using mixed methods. Contexts are scholastic and university ones, as well as formal and non-formal, like the Games Experiments Ideas (GEI) exhibition or theaters. Attention is paid to the disciplinary content and methods that establish physics, in epistemological terms, within a basic culture and in teacher education, with specific studies on the guidance and construction of active citizenship and university teaching innovation. The topics covered are classical physics, quantum mechanics, optical, atomic, nuclear and gamma spectroscopy, relativistic dynamics and superconductivity. For teacher education, the Metacultural-Experiential-Design-Situated (MEDS) model was developed with 20 years of experimentation.
