Designing a new model for science teacher training in Lebanon. - Within the framework of their training, nine biology student teachers are placed in a classroom situation and through the implementation fo some apparatus, they face the reality of construction and appropriation of scientific knowledge process by pupils reaching the level of formal thinking. The experiment gives them the opportunity of reconsidering some aspects of science teaching and of shaping a theoretical frame for the practise of their future profession. It allows the tutor to design a new model for Lebanese science teacher training and to outline the necessary conditions for this model to operate.