The purpose of the research is to study and change the structure of a mathematical lesson to improve quality of pupils' mathematical training and design mechanisms of inclusion the systems of open type tasks in educational process considering specifics of pupils' creative personality development. The leading method is modeling of a mathematical creative lesson. The structure of it contains such stages, as motivation, psychological relief, intellectual warm-up and resume, besides traditional substantial sections. More than 700 pupils from 5-9 grades of comprehensive school took part in the experiment, which has been carrying out for the last three years. The result of the research is the author's idea of using separate open type tasks, and the system of open type tasks, which consider psychological, physiological, motivational and cognitive features of pupils, promote development of their creative component for meta-subject results achievement. The practical use of the structure of a mathematical creative lesson and the systems of open type tasks shows pupils creative results and progress in mathematical training, expressed by best marks on the subject and at mathematical competitions of various levels. It proves the quality improvement of mathematical education among pupils trained by the offered technique.