Introduction. The development of the education system in recent decades has been accompanied by extensive informatization, activating the cognitive activity of students necessary for the formation of a successful educational process. To identify the impact of the use of an interactive whiteboard (ID) in adolescents of grades 5 and 7, a comparative study of the functional state of the body (FS) of schoolchildren with and without ID was conducted, which is an integral indicator of the ability of an individual's body to maintain a reserve of adaptive reserves under the influence of adverse factors. Mental performance indicators according to the letter table of Anfimov served as markers of FS, allowing to assess the FS of the central nervous system and its change under the influence of various factors. Therefore, the purpose of the study was to study mental performance and assess the body's FS and the emotional state of primary school students in lessons with and without the use of ID. Materials and methods. The study of the influence of the use of ID in educational activities on the mental performance and emotional state of 233 students of different sexes was conducted in a natural hygienic experiment at a secondary school in Moscow. The differences determined by the Student's t-test were considered significant at p<0.05. Results. The initial indicators of mental performance in girls and boys of grades 5 and 7 correspond to the standards for children of this age. When comparing the levels of working capacity in grades 5 and 7, it was revealed that fifth graders are almost 2 times more likely to have a high level of working capacity (p<0.01). And in grades 5 and 7, there is a tendency for girls to have a higher intensity of work than boys, and in grades 7 it is significantly higher (p <0.05). In the process of working with the use of ID, the coefficient of decrease in working capacity in students of grades 5 and 7 was higher than 1, and this indicates the tension of regulatory processes in the body, the impossibility of rapid restoration of functions in students of these age groups, especially girls. Conclusion. The results of the study show that the use of an interactive whiteboard increases educational motivation and emotionally activates the educational activities of students in grades 5-7. However, a comparison of the fatigue of two variants of lesson organization (with and without ID) with the same lesson density according to the distribution of individual shifts in mental performance showed that after lessons with ID, there is a higher percentage of fatigue and pronounced fatigue among students of the basic level of education, and gender differences were also revealed: for girls, classes using ID were more exhausting than for boys. The data obtained indicate that when using electronic educational tools in the educational process, it is very important to take into account the age, gender and individual capabilities of the body of students.