TY JOUR TI Project Activity in Primary School: Cooperation and Co-creation in the System "Parent - Child - Teacher" KW younger schoolchildren; project activity; the parent-child-teacher system; assistance KW cooperation KW co-creation; cognitive activity; universal learning activities JO Primary Education AU Petrash, E.A. AU Pradun, I.V. PY 2022 IS 10 PB INFRA-M Academic Publishing LLC.