Okla. Stat. tit. 25, § 153

It shall be the duty of the district boards or boards of education of every public school, or proprietor of a private or parochial school in this state, to provide a suitable flag of the United States of America with staff or flagpole for every schoolhouse, and cause the flag to be displayed during every school day either from a flagstaff or pole, and in inclement weather, within the school building. Laws 1939, p. 7, § 3.