Section 37. The school committee in each city and town and each regional school district shall have the power to select and to terminate the superintendent, shall review and approve budgets for public education in the district, and shall establish educational goals and policies for the schools in the district consistent with the requirements of law and statewide goals and standards established by the board of education. The school committee in each city, town and regional school district may select a superintendent jointly with other school committees and the superintendent shall serve as the superintendent of all of the districts that selected him.