METHODOLOGY OF DEVELOPING STUDENTS’ COGNITIVE ACTIVITY IN PRIMARY GRADE MATHEMATICS LESSONS ON THE BASIS OF PROBLEM-BASED LEARNING. Journal of Multidisciplinary Sciences and Innovations, [S. l.], v. 5, n. 02, p. 1288–1291, 2026. DOI: 10.55640/. Disponível em: https://ijmri.de/index.php/jmsi/article/view/5655. Acesso em: 1 jun. 2026.