Background: The World Health Organization recommends that children should participate in sufficient PA by engaging in moderate-to-vigorous physical activity for at least 60 min daily per week. Schools are important settings for the promotion of children's physical activity. Through commuting, break times, and physical education lessons they provide regular opportunities for children to be active. Methods: The experimental group included 26 girls and 24 boys aged 6-7 years old, and the control group included adolescent girls (n=25) and boys (n=23). The experimental group included 26 girls 24 boys aged 6-7 years old. Their mean weight and height were 24.3±0.9 kg and 1.25±0.11 m for the girls, and 29.3±0.6 kg and 1.33±0.09 m for the boys. The control group included 25 girls and 23 boys aged 6-7 years old, attending the same school. Their mean weight and height were 22.3±0.7 kg and 1.24±0.1 m for the girls, and 28.4±0.7 kg and 1.36±0.07 m for the boys. The methodology of innovative physical education classes was based on the DIDSFA model (dynamic exercise, intense motor skills repetition, differentiation, reduction of parking and seating, physical activity distribution in the classroom). The testing of physical fitness: The flexibility test, the long jump test, 3 × 10 m speed shuttle run test, a medical (stuffed) 1 kg ball pushing from the chest test. The evaluation of physical activity: Children's Physical Activity Questionnaire (Corder et al., 2009) was used. It was also based on the Children's Leisure Activities Study Survey (CLASS) questionnaire. Results: Experimental group (EG) (boys and girls) post-test results physical fitness (PF) tests, it turned out that the results of the long jump test ranged from 106.3 cm (girls) to 120.1 cm (boys), statistically significant differences were detected (p < 0.05). The girls (2.93 m) performed worse than the boys (3.64 m) (p < 0.05) in the medical (stuffed) 1 kg ball pushing from the chest test. The best score of the girls' 3 × 10 m speed shuttle run test was 8.55 s, for boys it was 8.8 s, the worst performance time for boys was 13.52 s, for girls 13.22 s (p < 0.05). Comparing the results of boys' and girls' flexibility, there were no statistically significant differences (p > 0.05): the girls' flexibility was about 0.06 cm, for boys -1.8 cm. The post-test of the experimental group boys (1261.93 MET, min/week) was to analyze average physical activity in comparison with the girls of the experimental group (737.48 MET, min/week). Statistically significant difference was found during the analysis of average MET per boy (1390.45 MET, min/week) in comparison with the girls (880.27 MET, min/week, p<0.05). Conclusion: Established that the properly construed and purposefully applied complex of the 8-month exercise intervention programme for first grade students caused the statistically significant changes in the dependent variables: increased physical activity and physical fitness for experimental group.