Yesterday, I talked about pre-World War II class size experiments. The experiments pretty uniformly concluded that small classes don’t help. What does the current research show?
Well, there’s one firm conclusion: The public loves the idea of small class sizes. William Howell, Paul E. Peterson and Martin West reported a couple of years back in Education Next that given the choice 77 percent of Americans would choose smaller class sizes over higher teacher salaries.
Does modern research support public opinion? Um, not so much. Most research finds that reducing class size has little or no benefit in terms of student outcomes. What we do know is that reducing class size is expensive. For example, reducing class size from 25 to 20 students requires a 25 percent increase in the number of classroom teachers.
While almost all research downplays the importance of reducing class size, there is one notable exception. The most famous class size experiment, the Tennessee STAR experiment, did show a real gain from class size reduction. So while the weight of the evidence is against spending to reduce class size, there’s not a complete consensus. That’s frustrating, but if we’re going to take an evidence-based approach we have to be willing to deal with evidence that isn’t always one-sided.
I still think it’s weird that that weight of scientific evidence and the weight of public opinion point in opposite directions.