Notwithstanding anything to the contrary in section 77 or in section 65B of the Education Act 1989, if the school’s board for the school district in which the school is situated, after consultation with the principal, so determines, any class or classes at the school, or the school as a whole, may be closed at any time or times of the school day for any period or periods exceeding in the aggregate neither 60 minutes in any week nor 20 hours in any school year, for any class, for the purposes of religious instruction given by voluntary instructors approved by the school’s board and of religious observances conducted in a manner approved by the school’s board or for either of those purposes; and the school buildings may be used for those purposes or for either of them.