The manual presents to readers some results of a long-term theoretical and experimental study of thinking, which acts as a meaningful mechanism for the development of activities. The methodological basis of the study is the genetic method implemented on comparative phylogenetic (higher primates) and ontogenetic (young child) material. The book poses the problem of forming an initial culture of thinking at an early and preschool age, proposes a system of games and activities aimed at enriching and generalizing the experience of subject mediation when a child solves the tasks of his activity.