Educational theory suggests that learning science follows the theory of social constructivism. This theory asks for organizing the teaching-learning-process in a student-active mode to be characterized by high individual as well as collaborative and cooperative student activity. This paper sums up essential tenets from this theoretical justification for more student-active learning in science. It discusses different dimensions of making the student more active in the science classroom as a theoretical underpinning of the EU-project TEMPUS-SALiS. The framework of the project will be presented.