Tex. Educ. Code § 45.084

The district may execute contracts for constructing or equipping school buildings in the district or for purchasing any necessary sites for school buildings in the manner provided by law. If any contract recites that payments under the contract are to be made either from the proceeds from the sale of real property under an installment sale agreement or any similar method pursuant to this subchapter or from proceeds from the sale of bonds issued pursuant to this subchapter, then the contract may be made payable in installments to correspond with the receipt by the district either of proceeds under the sale agreement or proceeds from the sale of any bonds to be issued and delivered in more than one issue, series, or installment, and the contract is not a prohibited debt or indebtedness of the district if the payments under the contract are required to be made solely from the proceeds from the sale of real property or the bonds.