The substance and forms of subject's activity in cognition are considered. Its sources, determinants, ways and conditions of its organization are described. Special attention is payed to education's role in the development of schoolchildren's cognitive activity, to making of different educational programs and forms of lessons. Subjective experience of students must be used for free choise of substance, forms and terms of education. It is stressed that student's activity is developed by special organization of education, including not only mastering a subject, but mastering effective ways of learning as well. The latter ensures self-development, self-realization of student's personality in continued education.