The text shows that after 1930, Vygotskij developed the question of teaching. Vygotskij forged new concepts, involving more systematic work on the dialectical contradiction between internal and external. An analysis of teaching work from a Vygotskian perspective shows the importance of transposed knowledge as a teacher’s tools. Elements of Vygotskij’s theory of development, elaborated after 1930, describe how educational tools function on the side of the student, allowing, through their appropriation, the construction of new psychic systems. This requires to reflect on the relationship between education and development, two totally different processes that Vygotskij conceptualizes through the notion of zone of proximal development.