This study suggests a training programme for in-service science teachers. The programme is based on active learning and aims to guide trainee teachers to engage active learning methods in their classroom practices. Research studies in the international literature appear to indicate the need for teachers to move away from traditional teaching approaches in order to engage students as active learners in the classroom. Furthermore, contemporary education has to face efficiently the needs of an increasingly diverse student population. Active learning methods could be efficiently taught to teachers by the use of these methods in their education. Thus, the student teachers not only hear and read about them, but they also experience them. The use of educational techniques that enhance active participation raises trainee teachers' reflection, increasing the chances of accepting new knowledge. Active learning theories stress the social elements of learning, e.g. the importance of cooperative action and collaborative problem solving, as tools of attaining deeper processes of learning and also achieving better results. Lesson study is an active learning method that ensures trainee teachers' engagement to the process, allowing them to construct personal and collective understanding. It permits teachers to collaboratively experiment with classroom practices while keeping students at the forefront of the procedure.