Class size refers to the ratio of students to teachers. Research has found that smaller class sizes are generally associated with better student outcomes, especially in elementary school. A famous Tennessee study in the 1980s found that elementary students in classes of 13-17 students achieved higher marks than those in larger classes. While the effects were smaller, smaller class sizes in middle and high school have also been linked to benefits like increased advanced coursework and lower dropout rates. However, larger class sizes allow schools to enroll more students and reduce costs. There is ongoing debate around the complex tradeoffs of class size and its impact on learning outcomes.