Small elementary classes

Class size reduction efforts reduce the ratio of students to educators in a classroom. Class size refers to the number of students assigned to a classroom; measures of class size do not account for the number of educators in the classroom, often called the student-teacher ratio. In K-3 elementary schools, the average difference between student-teacher ratio and classroom size in the 2013-14 school year was 9 or 10 students; an elementary school with a 16:1 school-wide student-teacher ratio had an average class size of 25 or 26 students (NEA-State rankings 2014).

Expected Beneficial Outcomes (Rated)

  • Increased academic achievement

Other Potential Beneficial Outcomes

  • Increased high school graduation

Evidence of Effectiveness

There is some evidence that smaller classes modestly improve academic outcomes (, Mosteller 1995, , , ), especially when implemented in kindergarten or first grade (, Brookings-Chingos 2011, CPE-Class size 2005, Watson 2013). However, class size reduction efforts typically have small effect sizes, perhaps due to continued use of teaching methods applied in larger classes (). Additional evidence is needed to confirm effects.

A small first grade class can modestly improve outcomes for students who were in larger kindergarten classes (). Overall, reductions in class size appear to benefit students who struggle in school more than high-achieving students, and smaller classes appear to have smaller achievement gaps than classes with more children (). Studies of Tennessee’s Student–Teacher Achievement Ratio (TN STAR) experiment indicate that small classes have the greatest benefits for children from low income households and minority students (, CPE-Class size 2005, Mosteller 1995), and improvements in reading skills among  minority students persist for at least five years (). Small classes from kindergarten to second grade may improve graduation rates for low income children, especially those who are placed in a small third grade class ().

Smaller classes appear to have modest positive effects on academic outcomes when teachers adopt teaching practices that take advantage of smaller class environments (Watson 2013), increasing individual attention and student-teacher interactions (). Class size reduction efforts also appear more likely to affect academic outcomes when implemented with professional development efforts that support teacher and staff use of teaching techniques, classroom management, and student interaction strategies suited to small class environments (Harker 2004, CPE-Class size 2005). Class size reductions may also improve student and teacher work environments ().

Class size reduction efforts frequently require additional classroom space (CPE-Class size 2005). Principals willing to fundamentally restructure school space can overcome space challenges. Principals can also deploy funding streams creatively to reduce class size (). Researchers suggest that many interventions can more cost effectively improve academic achievement than class size reduction efforts; tutoring and professional development are two examples (Brookings-Chingos 2011, ).

Impact on Disparities

Likely to decrease disparities

Implementation Examples

In 2009, 23 states had enacted policies to reduce class size to a level below 20 students per classroom; 15 of those states focus on students in grades K-3 (ECS-Zinth 2009). By 2010, 35 states had laws restricting the number of students allowed in a general education classroom. Following the economic downturn, however, 19 states relaxed or eliminated these laws (Ed Week-Class size 2011). 

In 2016, Arizona introduced a bill for a class size reduction and teacher retention program in grades K-3 (NCSL-Early ed tracking 2016).

Implementation Resources

Burch 2010 - Burch P, Theoharis G, Rauscher E. Class size reduction in practice: Investigating the influence of the elementary school principal. Educational Policy. 2010;24(2):330-58.

WI DPI-SAGE - Wisconsin Department of Public Instruction (DPI). Student achievement guarantee in education (SAGE) program.

Citations - Evidence

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Ding 2010* - Ding W, Lehrer SF. Estimating treatment effects from contaminated multiperiod education experiments: The dynamic impacts of class size reductions. Review of Economics and Statistics. 2010;92(1):31–42.

Nye 2004* - Nye B, Hedges LV, Konstantopoulos S. Do minorities experience larger lasting benefits from small classes? Journal of Educational Research. 2004;98(2):94-100.

Finn 2005* - Finn JD, Gerber SB, Boyd-Zaharias J. Small classes in the early grades, academic achievement, and graduating from high school. Journal of Educational Psychology. 2005;97(2):214-23.

Konstantopoulos 2011* - Konstantopoulos S. How consistent are class size effects? Evaluation Review. 2011;35(1):71-92.

Burch 2010* - Burch P, Theoharis G, Rauscher E. Class size reduction in practice: Investigating the influence of the elementary school principal. Educational Policy. 2010;24(2):330-58.

Reynolds 2010a* - Reynolds AJ, Magnuson KA, Ou SR. Preschool-to-third grade programs and practices: A review of research. Children and Youth Services Review. 2010;32(8):1121-31.

Cho 2012* - Cho H, Glewwe P, Whitler M. Do reductions in class sizes raise students' test scores? Evidence from population variation in Minnesota's elementary schools. Economics of Education Review. 2012;31(3):77-95.

Watson 2013 - Watson K, Handal B, Maher M, McGinty E. Globalising the class size debate: Myths and realities. Journal of International and Comparative Education. 2013;2(2):72-85.

Hattie 2005* - Hattie J. The paradox of reducing class size and improving learning outcomes. International Journal of Educational Research. 2005;43:387-425.

Harker 2004 - Harker R. Class size and student attainments: Research and strategic implementation. Massey University. 2004.

Bosworth 2014* - Bosworth R. Class size, class composition, and the distribution of student achievement. Education Economics. 2014;22(2):141-165.

CPE-Class size 2005 - Center for Public Education (CPE). Class size and student achievement: Research review. 2005.

Blatchford 2011* - Blatchford P, Bassett P, Brown P. Examining the effect of class size on classroom engagement and teacher-pupil interaction: Differences in relation to pupil prior attainment and primary vs. secondary schools. 2011;21(6):715-730.

Mosteller 1995 - Mosteller F. The Tennessee study of class size in the early school grades. The Future of Children. 1995;5(2):113-127.

Brookings-Chingos 2011 - Chingos MM, Whitehurst GJ. Class size: What research says and what it means for state policy. Washington, DC: Brookings Institution; 2011.

Citations - Implementation Examples

* Journal subscription may be required for access.

Ed Week-Class size 2011 - Education Week. Issues A-Z: Class size. Editorial Projects in Education Research Center. 2011.

ECS-Zinth 2009 - Zinth K. State policies focusing on class-size reduction. Denver: Education Commission of the States (ECS); 2009.

NCSL-Early ed tracking 2016 - National Conference of State Legislatures (NCSL). 2016 Early education legislative tracking. 2016.

Date Last Updated

Mar 30, 2016