Despite section 93 and any other provisions in this Act or in regulations made under this Act relating to the closure of schools, any 1 or more classrooms at the school, or the school as a whole, may be closed during the school day for any period or periods not exceeding 60 minutes in aggregate in any week or 20 hours in a school year, for the purposes of religious instruction or observances conducted by voluntary instructors approved by the school’s board.