The physics of the last century is now included in all EU secondary school curricula and textbooks, even if in not organic way. Nevertheless, there are very different positions as concern its introduction and students' conceptual knots in classical physics are quoted to argue the exclusion of modern physics in secondary school. Aspects discussed in literature are goals, rationale, contents, target students, instruments and methods. Very different goals, i.e. the culture of citizens, popularization, guidance, education, build different perspectives and aspects to treat selection: fundament, technologies and applications. Methods used are story telling of the main results, argumentation of crucial problems, integrated or as a complementary part in the curriculum. Modern physics in secondary school is a challenge, which involves curriculum innovation, teacher education and physics education research to individuate ways that allows the students to face the interpretative problems and manage them in many contexts and in social decisions. In this perspective, modern physics is an integrated content in curricula involving the building of formal thinking. Our research focus on building of formal thinking is on three directions: 1) Learning processes and role of reasoning in operative hands-on and minds-on phenomena interpretation; 2) object-models as tools to bridge common sense to physics ideas and ICT contribution focusing on real time labs and modelling; 3) building theoretical way of thinking: a path inspired of Dirac approach to quantum mechanics. We developed four different kind of proposals: 1) the physics of modern research analysis in material science: resistivity and Hall effect for electrical transport properties, Rutherford Backscattering Spectroscopy to look to structure characteristics, Time Resolved Resistivity for epitaxial growth; 2) Explorative approach to superconductivity phenomena (a coherent paths), 3) Discussion of some crucial / transversal concepts both in classical physics and modern physics: state, measure, cross section, 4) foundation of theoretical thinking in quantum mechanics.