Colo. Rev. Stat. § 22-31-125
Each director shall, no later than ten days after he or she receives the certificate of election pursuant to section 1-11-103, C.R.S., or appointment pursuant to section 22-31-129 (2), appear before some officer authorized to administer oaths or before the president of the board of education and take an oath that the director will faithfully perform the duties of the office as required by law and will support the constitution of the United States, the constitution of the state of Colorado, and the laws made pursuant thereto. The oath shall be filed with the designated election official for the school district. In case a director fails to take the oath within the period, the office shall be deemed vacant, and the vacancy thus created shall be filled in the same manner as other vacancies in the office of director.
C.R.S. § 22-31-125