Is there some point beyond which every student added to a classroom reduces the overall result? As a former teacher, I’ve watched the growing debate over class size in American primary and secondary education with interest and some alarm.

My instinctive response is that class size does matter and that we’re headed in the wrong direction, but does the evidence bear this out?

Are K-12 Classes Getting Larger?

Some educators have written about growing classroom sizes as a consequence of major funding cuts at the state level. A National Education Association study, for example, reported that funding cuts for education required increasing class size limits in Georgia and, similarly, that budget cutbacks in Fairfax County, Virginia, which already had larger than average class sizes, required increases that averaged about 0.5 students per class.

Many education writers agree: class sizes are growing generally all over the country. Grace Chen, writing in the Public School Review, concludes that "Many areas of the country are facing classrooms that are literally busting out at the seams."

But Is This Really True?

My assumption has been that the many articles describing increases in class size over the past few years — from, say, 2005 through 2018 — reflect an unfortunate reality.

However, a 2017 statistical analysis of classroom sizes worldwide from 2005 through 2016 by the Organization for Economic Cooperation and Development doesn’t bear this out, at least not to a degree that would justify the general consensus in education circles that U.S. classroom sizes are getting out of control.

The OECD statistics are as follows: In 2005, K-12 classes in the U.S. averaged 20.5 pupils per class. By 2010, the average had dropped to 20 before increasing in following years to a maximum of 21.1 (2013 through 2016). However, the following year, 2017, the average dropped to 20.8. To put this in perspective, class sizes in the U.S. have remained relatively stable over the past 15 years, with a maximum variation of 0.6 pupils, and as of the most recent year for which statistics are available, are only a small fraction larger than they were 15 years ago.

Then Why the Alarm?

One reason so many Americans are alarmed about class sizes is that the issue has become politicized in an increasingly partisan U.S. environment. Kevin Baker, writing in Politico, notes that every aspect of American life has become increasingly analyzed from either a liberal or conservative perspective in what he calls “the Age of Trump.”

But, the reality is that this didn’t begin with the current president. The several debates about U.S. education — class size being only one of several — were in full swing throughout both the presidencies of George W. Bush and Barack Obama, often in relation to The No Child Left Behind Act of 2001, but also occasioned by the federal government’s fitful financial support of not just the NCLB Act but of K-12 education generally.

To say that Americans have mixed feelings about the Act, and its successor, the Every Student Succeeds Act (ESSA), underestimates the vehemence of responses, many of them related to funding. The Act, you may remember, was supported by Republican President George W. Bush, but has generally been criticized by both the liberal and conservative press as well as the National Education Association for failing to give the states money to fulfill its requirements — a so-called "unfunded mandate."

If the federal government wasn’t fully paying for the costs of NCLB, then who would bear the costs? The ensuing "unfunded mandate" dispute has extended over nearly two decades and has aligned with and become a part of a larger conservative vs. liberal debate over state taxes.

Why Class Size Will Continue to Be an Issue

There are a few outlying opinions that class size doesn’t matter, but the general consensus among educators, much of it borne out by extensive research, is that it does. There’s less agreement about the ideal class size, but most educators agree that 30 students in a class is too many.

Since U.S classrooms have an average of fewer than 21, which is closer to the minimum in other countries (Costa Rica has only 15.4) than the maximum (Chile has over 30), why the continued fuss and alarm?

No one, of course, can provide a definitive, unarguable answer to the question, but it helps to see the class-size argument in a political context. For conservatives, the class size debate centers on the federal government’s unwelcome intrusion into state affairs; for liberals it becomes a graphic illustration of the triumph of money over democratic ideals.