The article consideres the possibility to develop six-year-olds by means of instructional activity. Two reciprocal streams of teaching are differentiated: development, and improvement, with their specific content and forms of cooperation of a student with the teacher and the peers. The determining reflection being the major new phenomenon in the junior school age is considered as the criterium of child's development by means of instructional activity. With a method which identifies children's ability to determining reflection there were examinations made among six-year-olds who were taught by means of instructional activity. The data obtained allows to conclude that six-year-olds can be taught by means of instructional activity, the conditions of development of both six and seven-year olds being similar, and the conditions of their improvement having qualitative differences.