Smaller Classes: They Can Help, But They're No Silver Bullet | Teachers College Columbia University

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Smaller Classes: They Can Help, But They're No Silver Bullet

Ask the average parent or teacher what change they'd most like to see in their school, and there's a good chance the answer will be "smaller classes." Now a new review of major research on the subject finds that reduced class size is far from a universal panacea...

Ask the average parent or teacher what change they’d most like to see in their school, and there’s a good chance the answer will be “smaller classes.”

Now a new review of major research on the subject finds that reduced class size is far from a universal panacea, and may have no bearing at all on student achievement unless enacted under the right political, economic and academic conditions. Those include quality teaching, targeting of schools and children likeliest to benefit, and avoidance of perverse incentives that can spawn unintended negative consequences.

“Class size reduction is not a silver bullet,” writes Douglas Ready, Assistant Professor of Education at Teachers College, ColumbiaUniversity, in his paper, Policy, Politics and Implications for Equity. “Establishing appropriate class size is a balancing act between children’s development needs and contemporary fiscal realities. The matter assumes even greater complexity when we consider the relationship between class size and educational equity.”

Ready’s review of the literature does show that poor and minority students are likelier to benefit from class size reduction efforts than white students and students from wealthier families.

Ready – a self-described “class size agnostic” -- chastises the media for its reporting on the issue. “Too often the class-size debates waged in the popular press and academic journals fail to reflect the complex and nuanced nature of the issue,” he writes. “For example, references in these debates to a ‘unitary class size effect’ ignores the absence of a unitary class size treatment.”

Ready presented findings from his paper at Teachers College on Wednesday, April 2nd, at Teachers College, ColumbiaUniversity.

Ready is the recent co-author (with Valerie E. Lee) of Schools Within Schools: Possibilities and Pitfalls of High School Reform. The designated respondents for Ready’s talk are Charles Achilles, professor of Educational Leadership at Eastern Michigan University and Seton Hall University, and a principal investigator in the famous Tennessee STAR Project class size reduction study; and Garth Harries, Chief Executive for Portfolio Development, New York City Department of Education, who is overseeing current class-size reduction efforts in the New York City public school system.

The presentation is the fourth in a series of “Equity in Education” forums being conducted by the College’s Campaign for Educational Equity, at which researchers summarize and identify areas for future inquiry the state of knowledge in various fields related to closing the nation’s school achievement gap.

A number of large-scale studies have demonstrated a powerful causal link between class size and student achievement. The best known is the Tennessee STAR Project, a study of 6,000 kindergarten students who were randomly assigned to small, medium and large classes up through third grade, and whose progress has been tracked into their high school years. By third grade, STAR students in smaller classes were performing at significantly higher levels in math and reading than other children in the study, and in high school they were likelier to complete advanced academic classes, take college admissions tests and graduate. Black students in the study who had been assigned to small classes were 25 percent more likely than black students in large classes to take and score higher on college admission tests.

But many quasi-experimental studies – research that, rather than randomly assigning students to different “treatments,” instead seeks to track them under real-life conditions – have failed to replicate these results. For example, a study of 650 elementary schools in Connecticut concluded that class size is unrelated to learning. And while Ready himself, in his own quasi-experimental research, has found evidence that smaller classes promote better learning, he notes that while the average U.S. class size has decreased by nearly 40 percent since 1970, student achievement nationwide has remained relatively stagnant (though the nation has undergone major demographic changes during that period, including a massive influx of immigration).

For Ready, the answer to this seeming paradox is that studies need to have both “internal validity” and “external validity” to be replicated. That is, a study must be able to legitimately demonstrate a cause-and-effect relationship for a given treatment within the population it is observing (internal validity), and that same treatment must be adaptable to other settings and contexts. The Tennessee study’s internal validity is unassailable, but because there was an extraordinarily high level of competence among participating teachers, the study is not “generalizable” to typical big-city public school systems or other settings.

Ready’s critique of efforts in California and Florida, two states that together have spent more than $20 billion on class size reduction, dramatically illustrates that point. While the jury is still out on direct cause-effect relationship between these efforts and student performance in the two states, Ready notes that – particularly in California, where the Governor’s decision in 1996 to reduce class size was a political move aimed at preventing surplus funds from being spent on teacher salaries – class size reduction has had a number of unintended negative consequences. For example, the number of uncertified K-3 teachers in the state jumped from less than 2 percent prior to the program’s implementation to 12.5 percent by the program’s second year. Among the schools serving the lowest-income students, the number of uncertified teachers grew to 20 percent. And overall 30 percent of teachers hired in California as a result of the class size reduction effort were uncertified.

In Florida, Ready notes, districts and schools can employ a wide variety of strategies to meet class-size reduction targets, including reducing graduation requirements and re-drawing school district boundaries.

Why, then, has class size reduction remained so popular in the public mind? Because, Ready says, it makes intuitive sense; because policymakers and elected officials have the power to enact it (unlike other school reforms, which can be initiated only through a more complex set of steps); because it can be (and thus far has been) applied to students of all income levels, ensuring its popularity with wealthier parents; and because it requires no change in how teachers teach. Yet it is that last attribute, Ready argues, that perhaps best explains why class size reduction alone can’t work miracles.

“Meaningful education reforms requires much deeper transformations than class size reduction alone can provide,” he writes. Size reduction itself demands “little of students, parents, teachers, schools, districts, or local and state governments. Unfortunately, reforms such as these that entail quantitative rather than qualitative change in the daily aspects of schooling rarely engender meaningful school improvements.”

To access Ready’s report or the podcast of the forum on April 2, please go to

Published Tuesday, Apr. 22, 2008


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