Nothing contained in this article shall be construed to prohibit or restrict a school official from receiving royalties or other compensation from the publisher or manufacturer of instructional materials written, designed, or prepared by such school official, and adopted or purchased by any governing board, other than compensation paid as commission to the school official for negotiating sales to governing boards. No district shall have or claim the right to receive any such royalty or other compensation due to any school official employed by the district unless the instructional material was written or prepared during the normal schoolday during which the school official is required by the district to be on duty.