If a school has no principal--
(a) any notice required or permitted to be given by or under this Act to the principal of the school, if given to any of the teachers at the school, is to be taken to have been given to every teacher at the school, and
(b) an obligation imposed by or under this Act on the principal is to be taken to be an obligation imposed on every teacher at the school, but which may be discharged by any one of them on behalf of them all.