This lecture explores the concept of constructivism, focusing on the stages of cognitive development according to Jean Piaget. It delves into the principles of assimilation and accommodation, cognitive conflict as a key learning mechanism, and the stages of cognitive development from sensori-motor to formal operations. The lecture also discusses the importance of learning from experience, learning by doing, and discovery learning. It emphasizes the role of cognitive conflict in learning and the transition from constructivism to constructionism, highlighting the use of tools like LEGO MINDSTORMS and Thymio in educational settings.