The purpose of the paper is to study the effectiveness of the use of informational and educational environment during the study of students of the training course Informatics to enhance their cognitive activity. The use of educational technologies with the use of ICT tools allows you to modify the entire teaching process, implement a model of student-centered learning, intensify classes by improving cognitive activity, and most importantly, improve senior students' self-training. The main tasks of modern pedagogical technologies using ICT tools are the development of interactive environments for managing the cognitive activity process, access to modern information and educational resources (multimedia textbooks, various databases, educational sites and other sources). The informational and educational environment is based on the integration of information on traditional and electronic media, computer-telecommunication interaction technologies, virtual libraries, distributed databases, educational and methodical complexes and an extended didactic device. In the concept of information-educational environment, the pedagogical system and its support are combined. The scientific novelty of the paper includes analysis of the works of scientists on increasing the cognitive activity of students through means of ICT and improving the forms of organizing classes in computer science using ICT tools. The article presents informational and educational environment for the study of computer science in secondary schools, namely Internet portal Virtual office of computer science and ICT. The purpose of creating an Internet portal is to coordinate the efforts of all participants in the educational process (students, teachers, parents), the organization of educational and non-academic work, as well as the activation of cognitive activity of students during the study of computer science. The practical value of the study is to refine the concepts of cognitive activity, educational activity, cognitive interest, the development and improvement of technology for raising senior students' cognitive activity by solving mathematical problems by means of computer mathematics at computer science lessons. The use of computer mathematics as an educational tool makes it possible to rethink traditional approaches to the study a lot of issues of computer science and mathematics, to increase the experimental activity of students, to bring the learning process closer to the real cognition process.