00601naa#a2200169#i#450# EN\\bibl\127563 20260718065337.6 1994-4683 20231031b2023####ek#y0engy0150####ca RU FEATURES OF ORGANIZING EXTRACURRICULAR ACTIVITIES IN MATHEMATICS AT SCHOOL Journal article Moscow National State University of Physical Education, Sports and Health named after P.F. Lesgaft 2023 3 с. Journal article local математики. 372.851 Lanina Svetlana Yurevna uchzapiski.lesgaft.spb.ru