Any school board of the state of Missouri, when it deems it a matter of public interest, may by two-thirds vote of its members join the Missouri School Boards’ Association and appoint one or more of its members to attend meetings called by the association within the state of Missouri. The school board may direct payment of the membership dues of the association and of the actual and necessary expenses incurred by members in attending the meetings called by the association from the incidental fund of the district.