Boards of education of city, exempted village, or local school districts may provide or approve, subject to the approval of parents, activities for children during the summer vacation period which will promote their health, their civic and vocational competence, and their industry, recreation, character, or thrift. The superintendents of such school districts shall cause records to be kept of such activities assigned and completed. With the approval of the state board of education the successful completion of such vacation activities may be required for promotions and diplomas of graduation, but the completion by any child of such vacation activities shall not be prerequisite to the issuance of an age and schooling certificate for such child. Boards of education shall provide the service necessary to direct such activities and may pay any necessary expenses incident thereto, the same as the expense of an ordinary elementary school.