Complex sentence: Classes were then held in the Quaker meetinghouse across the common until 1874, when a new building was completed, which would serve as the Weare school district from 1877 to 1938.
Split into simpler sentences: Classes were then held in the Quaker meetinghouse across the common until 1874, when a new building was completed. It would serve as the Weare school district from 1877 to 1938.