class size and level of achievement in school mid-1980s particularly in the early years according to the Center for Public Education (CPE) Class size an student achievement: Research review A review early elementary students most well-known a similar research review early elementary students class size and level of achievement in school Class size and student achievement: Research review class size Center for Public Education Research on Class Size improve academic achievement says significant evidence class size The Center for Public Education roundup of major studies on the question