The contribution will focus on a study carried out with prospective secondary school teachers, concerning the design and implementation of teaching materials aiming at guiding student-teachers (STs) in the transition from a teaching model based on a pre-fixed syllabus (that is a list of contents to be completely covered and presented to the students) to a model based on a teaching project (that is a conceptual path to be designed by the STs in the light of XXth century culture according to cultural and educational goals, based on a selection of disciplinary concepts and open to epistemological reflections).
The study is founded on a previous research work aimed at re-constructing Classical Mechanics, Special and General Relativity from an educational perspective, in which disciplinary aspects are integrated with historical-epistemological and cognitive ones.
The core structure of the produced materials is a set of conceptual paths, designed on the basis of the following criteria:

• privileging the quality of knowledge rather than the quantity of notions to be transmitted;
• addressing topics and questions of XXth century Physics on the basis of a “modern teaching” of classical Physics;
• fostering an image of Physics as “cultural product” characterised by the co-existence of different interpretations of the same formalism and by the interconnections with other cultural fields;
• fostering the creation of a flexible learning environment in which each student is encouraged to find his/her own path and to construct his/her cultural, cognitive and emotional growth.

The obtained results allow us to point out the conditions in which the history and philosophy of physics in pre-service teacher education can become real teaching tools for interpreting and solving cognitive obstacles that students can meet passing from classical to modern Physics.
The study is part of the Italian National Project FFC (coordinated by P. Guidoni) and the produced materials will be collected and re-organised in a web-site both for pre-service and in-service teacher education.