§ 2042. Form and validity of contract. Every contract for the education of school children shall be in writing and in the form prescribed by the commissioner of education, and before such contract is executed the same shall be submitted for approval to the superintendent of schools having jurisdiction over said district and such contract shall not become effective until approved by such superintendent. Such contract shall not be valid or binding upon either party thereto until a copy thereof is filed with the commissioner of education and approved by him.