Whenever the school board, by a two-thirds majority of its members shall find and declare the following propositions and shall cause to be recorded in the Recorder’s Office a certificate embodying such findings and declarations duly signed by its president and attested by its secretary or clerk, then said school board may cause the exchange of a present school site or site with building thereon for a substitutional site without a referendum approving such exchange. The above findings and declarations shall establish the following: (1) That in the opinion of the school board a school site or site with building thereon has become unsuitable or inconvenient for a school; (2) that a substitutional school site has been offered in exchange for the present site which is a suitable, convenient and desirable site for a school and (3) that the value of the substitutional site is equal to or exceeds the value of the present site for which it is to be exchanged, the criterion of value to be that of a fair market value. When such certificate has been recorded as aforesaid, the school board shall transmit a copy of said certificate to the trustees of schools or other school officials having legal title to such land and shall request the execution of a deed of conveyance by the president and clerk, or secretary, as the case may be, to be delivered upon the receipt of a good and sufficient deed conveying to the trustees of schools or other school officials entitled under the statute to hold legal title to lands in the particular school district a good title to the substitutional site; and such president and clerk, or secretary, as the case may be, shall comply with such request. If the school board of a school district holds legal title to any lands to be exchanged under this Section, the certificate shall be recorded by the school board, and the deed of conveyance shall be executed by the president and by the secretary or clerk of the school board, as the case may be, and shall be delivered when a good and sufficient deed conveying the legal title of the substitutional site to the school board is delivered to the school board. The certificate provided for shall set forth an accurate legal description of the present school site and of the substitutional site offered as aforesaid.