Class size study

Reduced class size doesn't level the playing field
Reducing classroom size to fewer than 18 students per teacher benefits high-achieving students more than struggling ones, according to an analysis by a Northwestern University researcher of data gathered in a major study on the interplay of class size and learning. "While decreasing class size may increase achievement on average for all types of students, it does not appear to reduce the achievement gap within a class," said researcher Spyros Konstantopoulos.
Konstantopoulos, S. (2008). Do Small Classes Reduce the Achievement Gap between Low and High Achievers? Evidence from Project STAR. Elementary School Journal, 108, 4.