The authority of the county board of education is limited by the rules and regulations of the state board of education as enforced by the commissioner of education. It is the duty of the state board to prescribe rules and regulations for all public schools, kindergarten through the 12th grade, to prescribe curricula, and to approve courses of study adopted by local boards of education. T.C.A. § 49-1-302. The state regulations extend to such matters as personnel evaluation, classroom size, pupil-teacher ratios, building suitability and other matters that directly impact the budget process.