Complex sentence: The new school opened in September 1917 with 304 students; the former high school became a junior high school, and then an elementary school in 1937, and it burned down in 1950.
Split into simpler sentences: The new school opened in September 1917 with 304 students. The former high school became a junior high school, and then an elementary school in 1937, and it burned down in 1950.