105 ILCS 5/34-74

Except as provided in Article 34A and Section 34-29.2 of this Code, all moneys raised by taxation for school purposes, or received from the state common school fund, or from any other source for school purposes, shall be held by the city treasurer, ex-officio, as school treasurer, in separate funds for school purposes, subject to the order of the board upon (i) its warrants signed by its president and secretary and countersigned by the mayor and city comptroller or (ii) its checks, as defined in Section 3-104 of the Uniform Commercial Code, signed by its president, secretary, and comptroller and countersigned by the mayor and city comptroller.