Reducing class size has become a perennial education improvement strategy, often popular with teachers and parents for its ability to give teachers more individual instructional time with students. Yet as states and districts struggle with tight budgets, more policymakers and researchers have begun to turn away from straight class-size reduction in favor of other methods to increase individual instruction time, such as restructured class formats, co-teaching, and distance learning.

Reducing class size gained prominence as a federally supported school-improvement strategy in 2000, with the creation of a federal class-size-reduction program, which gave states funding to recruit, hire, and train new teachers. Under the reauthorized Elementary and Secondary School Act—also known as the No Child Left Behind Act of 2001—that program was consolidated into a more general teacher-quality block-grant program funded at $2.85 billion for 2002.

The national ratio of students to teachers in public schools fell between 1980 and 2008, from 17.6 to 15.8 students per teacher, according to the National Center for Education Statistics. However, because the statistics count special education and other specialized teachers who normally have much smaller classes than regular classroom teachers do, the U.S. Department of Education estimates the current average class size is closer to 25 students (Sparks, 2010).

In Quality Counts 2008, the EPE Research Center found that 21 states had a class-size reduction policy in place for the 2007-08 school year. By 2010, all but 15 states had laws restricting the number of students that may be included in a general education classroom, in some or all grades. Following the start of an economic downturn in 2008, 19 states relaxed or eliminated their class-size laws or policies, usually as a cost-saving measure (Sparks, 2010; Dorko, Sparks, 2010).

Likewise, states and districts have begun to shift their use of the federal teacher-quality block grants away from class-size reduction measures. According to an analysis by the Washington-based think tank Center for American Progress, 38 percent of districts surveyed in 2008-09 used the grants, called Title II, Part A funds, to reduce class sizes, but overall, the number of teachers whose jobs were underwritten by those grants decreased by 40 percent between 2002-2003 and 2008-2009. (Chait, 2009)

Research, for the most part, tends to support the belief in the benefits of small classes. While not all studies on the subject have shown that students learn more in smaller settings—and some are still ongoing—most have linked smaller classes to improvements in achievement.

The biggest and most credible of those studies, Tennessee’s statewide Student/Teacher Achievement Ratio, or STAR, project, begun in the late 1970s, found that the learning gains students made in classes of 13 to 17 students persisted long after the students moved back into average-size classes (HEROS, 2011). What’s more, the Tennessee researchers found, poor and African-American students appeared to reap the greatest learning gains in smaller classes. After kindergarten, the gains black students made in smaller classes were typically twice as large as those for whites. Follow-up studies through the years have found the students who had been in small classes in their early years had better academic and personal outcomes throughout their school years and beyond (Krueger, 2001; Sparks, 2011).

Likewise, a 2001 evaluation of the Student Achievement Guarantee in Education, or SAGE, class size reduction program by researchers at the University of Wisconsin-Milwaukee found that a five-year-old program of class-size reduction in Wisconsin resulted in higher achievement for children living in poverty. Research from Columbia University Teachers College in New York showed the context of class-size reduction can affect its success in improving student achievement (Ready, 2008). Similarly, Charles M. Achilles, one of the original principal researchers on the STAR study, has said researchers and policymakers will have difficulty replicating the improvements seen in the STAR study without including key elements of that program, such as early intervention and small class sizes of three years or more (Achilles, 2008).

Researchers agree that shrinking the number of students in a class does not automatically translate into better learning. To squeeze the most out of their new settings, teachers may need to alter their teaching practices, dropping lecture-style approaches and providing more frequent feedback and interaction. And, while the studies that found positive effects from class-size reductions have focused on efforts that cut classes down to 16 or so students, states have so far tended to reduce classes only by a few students.

As school improvement ideas go, reducing class sizes is costlier than many others and more complicated than it appears at first blush. For example, Florida estimates its class-size program will cost $40 billion to implement through 2020. An analysis of 24 state policies by the Brookings Institution’s Brown Center on Education Policy found many of those initiatives may not be worth the cost because the average class-size reductions were not large enough to improve student achievement (Whitehurst, 2011).

One concern surrounding efforts in various states to shrink class sizes is that the press for quantity will come at the expense of quality, forcing schools and districts to hire underqualified or unprepared teachers.

California learned that lesson firsthand when the state undertook its own class-size-reduction initiative beginning in 1996. In the first year of implementation, more than one-fifth of the new teachers hired in that state had only emergency credentials. Hit hardest were schools serving poor and minority students. In the hunt for new space, administrators found themselves carving classrooms out of broom closets and erecting portable classrooms on playgrounds.

It remains to be seen how much federal support will be given to class-size reduction programs in the next iteration of the Elementary and Secondary Education Act. U.S. Secretary of Education Arne Duncan has voiced a preference for expanding school days and years to increase instructional time over reducing class sizes. He cited statistics from the Organization for Economic Cooperation and Development, a Paris-based group representing major industrialized countries, showing that several high-performing Asian countries have higher average class sizes: 33 in Japan and 36 in South Korea, compared with the estimated 25 students in the United States.