Complex sentence: A four-year junior college was a type of educational institution in the United States in the 20th century that provided education from the 11th to the 14th grades, corresponding to the last two years of high school and the first two years of college.
Split into simpler sentences: A four-year junior college was a type of educational institution in the United States in the 20th century. It provided education from the 11th to the 14th grades, corresponding to the last two years of high school and the first two years of college.