The treasurer of each school district shall receive all State appropriations, district school taxes, and other funds belonging to the school district, and make payments out of the same on proper orders approved by the board of school directors, signed, except in districts of the first class, by the president, and, in any school district of the first class by the secretary. The treasurer may pay out such funds on orders which have been prepared and signed by the secretary, and in school districts other than in school districts of the first class, signed by the president, without the approval of the board first having been secured, for the payment of amounts owing under any contracts which shall previously have been approved by the board, and by the prompt payment of which the district will receive a discount or other advantage. In all school districts of the first class, all school orders before being paid by the school treasurer shall be approved by the school controller of such district.