Original sentence: Based on this evidence, the school in 1984 officially moved up its founding to 1628.Collegiate states it is the oldest school of any kind in the United States.It claims to be the oldest school in the United States.Prior to 1984, the common belief was that the school had been founded in 1638, placing it two years later than the founding of Harvard University and three years after the founding date of Boston Latin School
Edited sentence: Collegiate claims it is the oldest school of any kind in the United States.It claims to be the oldest school in the United States, although that assertion is disputed.The school was founded in 1626, placing it six years earlier than the founding of Harvard University  in 1636.While there is no evidence of a formal school being established prior to the 1638 date, in 1984 Collegiate officially moved up its founding to 1628