Section 43. The city council may, of its own motion, and shall, upon request of the school committee if a measure originates with that committee and pertains to the affairs under its administration, submit to a vote of the registered voters of the city for adoption or rejection at a general or special city election any proposed measure, or a proposition for the repeal or amendment of any measure, in the same manner and with the same force and effect as are hereby provided for submission on petition.