There shall be a school committee consisting of five (5) members elected for terms of three years each, so arranged that the term of office of as nearly an equal number of members as is possible shall expire each year. The school committee shall have general charge and superintendence of the public schools and for this purpose shall have all of the powers and duties which are given to school committees under the constitution and laws of the Commonwealth of Massachusetts, and such additional powers and duties as may be authorized by the charter, by by-law or by other vote of the town meeting.