This chapter describes the theoretical foundations of the educational project “Transformations” aimed at developing of dialectical thinking in preschoolers and based on the “child’s participation principle” in the educational process. Dialectical thinking is understood as productive operating with opposites which allows, on the one hand, to understand the world as evolving and developing, and, on the other, to produce a new creative product. The key points of the project are discussed: the dialectical structure of the developing world as an educational content, a dialectical problem, and the child’s participation principle. The author explains the specifics of implementing of the “child’s participation principle” in the “Transformations” project, in particular, a child’s mastering of cognitive tools required for the comprehension of development processes. It is especially important for forecasting, planning and reflecting, also in the life of the child.