00560naa#a2200169#i#450# EN\\bibl\18730 20240809102631.5 2541-822X 20171228b2017####ek#y0engy0150####ca RUS RU TECHNIQUES OF SYSTEM-ACTIVITY APPROACH IN SECONDARY SCHOOL Journal article Cheboksary Non-state educational private institution of additional professional education "Expert-methodological centre" 2017 2 с. Journal article local Kovalchuk Elena V. naukaru.ru