Reducing class size in the early grades -- kindergarten through second grade -- to under 20 students per class raises student achievement, according to an article in "Great Schools." The gains are particularly noticeable for minority students, immigrant students and students with a low socioeconomic status. With smaller class sizes, teachers are able to get to know their students better, and can build stronger relationships, according to a study done by two Princeton University professors. The Princeton study also noted students who were in schools with smaller class sizes scored higher on achievement tests, even when they were no longer in a smaller-class-size model school.