Complex sentence: Thereafter, Stuyvesant became renowned for excellence in math and science: as early as 1909, eighty percent of the school's alumni went to college, compared to other schools, which only sent 25% to 50% of their graduates to college.
Split into simpler sentences: Thereafter, Stuyvesant became renowned for excellence in math and science. In 1909, eighty percent of the school's alumni went to college, compared to other schools, which only sent 25% to 50% of their graduates to college.