Structural components of textbooks used by schoolchildren as means of self-control have been first critically analyzed and then used by the authors in an experimental attempt to promote development of the corresponding skill. A new structural component - "answer" has been suggested and introduced1 in order to implement control over the development. The difficulty of using answers is to be gradually increased. Proper succession of introduction of means of self-control, which also contribute to development of the corresponding skill in schoolchildren, is given. Presence of such means in a textbook makes its structure more flexible and efficient.