Compelling evidence demonstrates that reducing class size, particularly for younger children, has a positive effect on student achievement overall and an especially significant impact on the education of disadvantaged children. The American Federation of Teachers is a strong advocate for reducing class size to help raise student achievement, especially in high-poverty, at-risk schools.

Large gains in both math and reading stem from more effective teaching and more focused learning. More teacher-student interaction allows teachers to recognize the needs of individual students and customize instruction and assignments. Teachers know the students better and can recognize problems and special needs early. For their part, students are more likely to be on task and less likely to talk amongst themselves. They create fewer discipline problems and engage in more pro-social behavior, allowing teachers to devote more time to instruction and less to controlling the class. Smaller classrooms are more pleasant and have fewer distractions.

As participants in early class size experiments enter the workforce, researchers have found long-term effects of small classes in the early years. Students with two or more years of small classes in elementary school score higher on tests in middle and high school, are more likely to graduate and are more likely to take the SAT or ACT and apply to college. They are also healthier and eventually earn more, paying more taxes and receiving less welfare.

Consensus on the benefits of small classes has led parents, teachers, administrators, policymakers and politicians to adopt some form of class size reduction in all but six states. Simply cutting class size does not guarantee significant increases in performance for all students, however. The AFT supports class size reduction plans that:

1. Aim for classes between 15 and 19 students each. Schoolwide or districtwide averages mean that some students remain in classes far exceeding the optimal size.
2. Target schools with low-achieving and low-income students. "One size fits all" class size plans neglect staffing problems and overcrowding in low-achieving schools, which gain the most from class size reduction.
3. Have a thoughtful implementation plan so that districts have the time and money to provide adequate classroom space and hire highly qualified teachers.

Supporting Research

Project STAR
Tennessee's Project STAR (Students-Teacher Achievement Ratio) was designed to determine the short- and long-term effects of small class size in grades K-3 on student performance. Findings

Student Achievement Guarantee in Education (SAGE) Program
SAGE began in Wisconsin in 1996 by phasing in class size reduction in grades K-3 in school districts serving high-poverty students. The aim is to achieve a student/teacher ratio of 15:1. Findings

Rouse Study
The Milwaukee Parental Choice Program is a publicly funded voucher program. In her study, Rouse compares the achievement of Milwaukee voucher students and students in three types of Milwaukee Public Schools: regular schools, magnet schools, and schools participating in the Preschool to Grade 5 Grant Program (P-5 schools). Findings

Wenglinsky Study
Educational Testing Services (ETS) researcher Harold Wenglinsky compared 1992 fourth- and eighth-grade NAEP math results to class size and other policy initiatives. For purposes of the analysis, Wenglinsky defined small class size as fewer than 20 students. Findings

Class-Size Reduction (CSR)
During the mid-1990s, the California Legislature passed the Class-Size Reduction (CSR) incentive program, which provided funds to schools statewide that set class size at 20 students in grades K-3. Findings

International Research

Maimonides' Rule, Israel
Due to rabbinic scholar Mainmonides' interpretation of the Torah regarding education, Israel has capped class size at 40 since 1969. This means that a grade of 80 students will have two classes of 40 each, but a grade of 81 students will have class sizes of 27, 27 and 26. The wide and random difference in class size provides a natural experiment. Findings

Institute of Education Class Size Study, University of London
Researchers randomly selected 11,386 students in the United Kingdom and followed them from the age of 4 to 7, recording demographic variables along with class size and test scores. Teachers were surveyed about how they spent classroom time, and researchers systematically observed selected classrooms by noting interactions every 10 seconds. Findings