Formation and development of personality through instruction in public school still remains in many respects a theoretical problem. Children found to be lacking in respect to the "age standard" are probably the worst off. The existing system of correction and development through instruction determines organizational aspects, but has nothing to offer in the area of specific courses. Nowadays there are over fifteen courses in mathematics, but none aiming at correction and development. The article de-scribes a conception for a course of instruction aimed at development of children by means of mathematics. The course is based on constructing a system of the child's modeling actions with the material being studied. An effective instructional technology and relevant course books have been developed on the basis of the conception.