The Bill & Melinda Gates Foundation has spent billions to determine how to best improve student achievement. Its conclusion was that its focus would be on improving teachers’ performance.

The foundation director cites a Los Angeles district study which found that “putting a great teacher in a low-income school helped students advance a grade-and-a-half in one year. An ineffective teacher in a high-income school held student achievement to about half-a-grade of progress in a year.”

In 2011, the Brookings Institute published an in-depth comparison of studies, costs and policy options. It found the greatest impact of small classrooms for early learning was with least-advantaged students. Study results varied from beneficial to neutral to, occasionally, negative impacts from smaller class size. Often the studies have not accounted for other factors, such as economic status.

Decreasing average class size across the United States by one student would require Title I funding to double. Brookings summarizes: “There are a small number of variables in American K-12 education that are both thought to influence student learning and are subject to legislative action. Class size is one. Others include human resource policies, funding levels, curriculum, days/hours of instruction and testing and accountability. Advocates for legislation on any of these topics are likely to appeal to research evidence as support for their position. That is appropriate and desirable as long as: a.) the evidence is of high quality, b.) it is relevant to the legislative action under consideration, c.) conflicting evidence isn’t ignored, and d.) alternative courses of legislative action are similarly evaluated and compared.”

In 2018, other researchers compared 148 studies. They found that students in small classes were 3% more likely to have better reading scores and slightly less likely to have better math scores, though the negative effect was not significant. Authors recommended that alternative interventions may provide a greater impact on reading scores than class size. 

Another study found that outcomes varied by school. Students in more schools did benefit from small class sizes. Other schools showed neutral or negative impact of small classes. Still another study found that reducing class size did not help until the ratio was 1:1 — individual tutoring. 

What does all this mean? It may suggest that struggling students need more individual tutoring, especially if they are less advantaged. Most students are likely to benefit from ensuring they have outstanding teachers. Research does not appear to create a compelling case for small classrooms at any cost.

Jeanne Dietsch of Peterborough is a former Democratic state senator and the current director of Granite State Matters.