The publication is devoted to the problem of assessing knowledge and skills. Students acquire them by studying the mathematical specialties of pedagogical universities. For example, we took the discipline „Elementary Mathematics”.When the teacher puts an evaluation on the subject, then this evaluation by the majority of people is understood as the level of the pupil's competence in this subject. But in fact, a marked number of balls precedes the painstaking evaluation activity in the control of the student during the study of a fixed subject. The article answers the question „What should be the controlling activity so that its result is a resource for regulating the learning process?”.