Аннотация
This article attempts to consider the value of the P. I. Galperin’s theory on phased formation of mental actions and concepts as the first stage in the development of the assimilation activity theory of social experience and to show the relevance of using it as the method in order to study the formation of human mental activation. The study presents significance of the fundamental assumptions of the theory of staged (planned) formation of mental actions by P.I. Galperin for the further development of the activity theory of learning The importance, relevance and effectiveness of the use of the theory of systematic step-by-step formation of mental actions and concepts created by P.I. Galperin in general practice of teaching and in the practice of school education, in particular, as well as other forms of education are substantiated. The role and importance of the scientist in the systematization of the so-called basic characteristics of subject-specific skills, methods of their development, as well as the connection of these characteristics with the actualization have been indicated. Thus, more than 60-year history of existence and development of the theory of step-by-step (planned) formation of mental actions of P.I. Galperin gives all grounds to assert that scientifically grounded use of this approach allows to successfully realize many theoretical and methodological and practical problems. Key words: activity approach, psychological theory of activity, activity theory of teaching, theory of step-by-step (planned) formation of mental actions, structure of activity.