; or (4) purchasing carbon offsets. 302. Supplement, not supplant A local educational agency receiving a grant under this Act shall use such Federal funds only to supplement and not supplant the amount of funds that would, in the absence of such Federal funds, be available for modernization, renovation, repair, and construction of public school facilities. 303. Prohibition regarding State aid A State shall not take into consideration payments under this Act in determining the eligibility of any local educational agency in that State for State aid, or the amount of State aid, with respect to free public education of children. 304. Maintenance of effort (a) In general A local educational agency may receive a grant under this Act for any fiscal year only if either the combined fiscal effort per student or the aggregate expenditures of the agency and the State involved with respect to the provision of free public education by the agency for the preceding fiscal year was not less than 90 percent of the combined fiscal effort or aggregate expenditures for the second preceding fiscal year. (b) Reduction in case of failure To meet maintenance of effort requirement (1) In general The State educational agency shall reduce the amount of a local educational agency’s grant in any fiscal year in the exact proportion by which a local educational agency fails to meet the requirement of subsection (a) of this section by falling below 90 percent of both the combined fiscal effort per student and aggregate expenditures (using the measure most favorable to the local agency). (2) Special rule No such lesser amount shall be used for computing the effort required under subsection (a) of this section for subsequent years. (c) Waiver The Secretary shall waive the requirements of this section if the Secretary determines that a waiver would be equitable due to— (1) exceptional or uncontrollable circumstances, such as a natural disaster