No real or personal property or improvements shall be purchased, leased, exchanged, acquired or sold, nor any schoolhouses built, remodeled or removed, nor any indebtedness incurred or money expended for any of the purposes of RCW 28A.335.250 through 28A.335.280 except in the manner otherwise provided by law for the purchase, lease, exchange, acquisition and sale of school property, the building, remodeling and removing of schoolhouses and the incurring of indebtedness and expenditure of money for school purposes.