Background. Studying the bioelectric activity of the brain allows scientists to get a picture of brain functioning, including cognitive activity. The sensitivity of this method allows identifying and explaining subtle differences between children with different academic success, representatives of the age norm. However, additional research is needed to develop and substantiate measures of psychological and pedagogical support for schoolchildren for increasing their academic success. Aim. The paper aims to study rest and cognitive load EEG data in 12-year-old children and assess the compliance of these data with the age norm. Materials and methods. Twelve-year-old children participated in the study, both males (n = 25) and females (n = 26). The EEG was recorded using the CONAN-m equipment, and the electrodes were mounted according to a 10–20 system. The study was carried out under four experimental conditions: at rest and under cognitive load, which consisted of solving three types of tasks (verbal-logical, arithmetic, and spatial rotation of a figure). EEG spectral characteristics were evaluated depending on the recording conditions. Results. It was found that predominant alpha-range frequency in females was from 9.6 to 9.8 Hz, in boys it was slightly higher (about 9.9–10.1 Hz). Response to cognitive load was slightly different depending on the type of task. In general, it consisted of a slight increase in theta and beta ranges and a decrease in bioelectric activity in the alpha range. In males, an asymmetric, cross-type activation was found with a more pronounced alpha rhythm depression in the left frontal, temporal and right occipital regions. Conclusion: In general, the examined sample corresponded to the age norm according to rest and cognitive load EEG.