Most parents agree that kids are going to learn better and faster in a smaller class than in a large one. But not everyone agrees that this is so, despite the fact that the largest study on the effect of class size to date demonstrates that “small classes appear to benefit all kinds of students in all kinds of schools.”

The Opposition

Some of the pooh-poohing about significant improvements in learning outcomes through class-size reduction comes from anti-tax conservatives. But the opposition is less predictable politically than you may think.

One of the more trenchant critiques appeared in 2018 in the technological and education-oriented THE Journal,which concluded that “class size doesn’t matter,” and that in at least one area, mathematics, outcomes improved as class sizes increased.

Since 2008, in fact, class sizes have begun increasing again. This has been, I believe, partly in response to the difficulty of adequately funding K-12 initiatives during and following the Great Recession.

Class sizes that had dwindled by about 25% from 1970 to 2008 are now back up to a little over 20 (in the lower grades) and nearly 27 in secondary school. But articles like The Journal’s “Meta-Analysis: Class Size Doesn’t Really Matter,” have contributed fuel to lawmakers’ reluctance to put more money into classroom reduction.

Who’s Right?

Two of the most detailed studies on class size largely disagree. THE Journal’s survey, based on 127 studies in 41 countries concludes that, at best, smaller class sizes result in slight, but statistically significant, improvements in reading. In other areas, either the improvements were less than statistically meaningful, there was no improvement or, as with math, reductions in class size actually worsened results.

An earlier study from 2000, which was even more detailed, came to the opposite conclusion. This four-year, large-scale research initiative, conducted by the Center of Excellence for Research and Policy on Basic Skills, concluded that “shortcomings in implementation” account for most of the continuing underestimates of the positive effects of smaller classes.

The study seems meticulously designed to separate valid conclusions from those that aren’t. I won’t put us all to sleep describing it in its actual detail. For that, you can go to the American Educational Research Journal.

Trust me, it’s a very detailed study with safeguards that only dedicated researchers would even think of. While the improvements in test results resulting from smaller class sizes aren’t dramatic, the researchers concluded that they are both significant and consistent, especially in the earlier grades.

How Should You Respond to These Conflicting Conclusions?

As both a former teacher and a parent, my inclination is to err on the side of the proposed benefit: while studies of classroom size are inconsistent, the largest scale study to date demonstrates improved outcomes when class sizes are 20 students or less.

This may be less significant in secondary school, although (again, as a former teacher, I know), keeping some kind of order among more than 20 teenagers in a small room without any kind of architectural noise control is exhausting. You might consider supporting smaller classes not just because it improves student outcomes, but because It slows the alarming attrition rate among primary and secondary teachers.

As I’ve noted in earlier articles on U.S. education, about half of all K-12 teachers quit within five years.

When you consider that each of these teachers spent at least four years of college learning how to become a teacher and (as I know) even after four years of college, spending more years of before really coming close to maximum competence, this drop-out rate represents an appalling waste of human capital, one that represents an ongoing American crisis. And class size is one of the most-cited reasons that teachers drop out.

All in all, you’re better off supporting class size reduction.