With the active introduction of information technology in the educational sphere, approaches to the textbook as the main means of presenting educational material have changed. Along with printed publications, electronic ones began to be actively used, which in their development have already gone from a simple text document to a complexly structured system that includes various ways of presenting educational material (text, audio, video, graphics). Their use today requires detailed study and reasonable implementation in professional training of specialists. The purpose of the article is to describe a pedagogical experiment on the effectiveness of using an electronic textbook in the training of computer science teachers. To achieve this goal, the following methods were used: theoretical: analysis of special literature on the problems of introducing electronic educational resources; generalization and systematization of domestic and foreign experience in the use of electronic textbooks in the process of training of computer science teachers, personal pedagogical experience in using electronic educational resources in the educational process; methods of mathematical statistics for the quantitative and qualitative analysis of the results of the pedagogical experiment (c2 Pearson, Student). The corresponding results for the author's ET "Information Systems" by criteria c2 Pearson, Student are given. Calculations for the positions are described: 1) availability (clarity) of the author's ET; 2) evaluation of the results of independent work based on the author's ET.