Okla. Stat. tit. 70 § 6-108
Except for service as a director of a public developmental research school and service by a faculty member of a higher education institution affiliated with a public developmental research school as specifically authorized in this act and except as provided for in Section 6-101 of this title, it shall be unlawful for any person to serve, or to contract or agree to serve, as superintendent, elementary superintendent, principal, supervisor, librarian, school nurse, classroom teacher or other instructional, supervisory or administrative employee of a school district unless the person holds a valid certificate of qualification issued in accordance with the rules of the State Board of Education to perform the services the person performs or contracts or agrees to perform. The State Board of Education shall provide for the certification of elementary superintendents.
Okla. Stat. tit. 70, § 6-108