Superintendents, principals and persons in charge of schools and attendance officers may administer oaths and take the affidavits of parents, guardians or other persons having charge, control or custody of children, concerning the ages of children, and furnish children with certificates of the affidavits. The certificates must have attached the signature of the child for whom it is issued, the signature of the persons who made and took the affidavit, and the seal of the school board of the district and shall contain the description of the color of eye and hair of the child to whom it is issued.