Many schools across America must take the budget bull by the horns and decide whether cutting class size is the right way to do it. Take the Fairfax County Public Schools, for example. Class size is set to go up next school year under Superintendent Garza’s proposed budget. Does it matter?

Financially, yes. Class size is a major driver of school costs. And increasing pupil/ teacher ratios by just one student would save an estimated $10 billion or more in teacher salaries nationally.

Effects on student achievement are less clear. Large jumps in class size would be detrimental, but mainly for students in very early grades. Above grade 3, the harm is minimal. But Garza’s proposed class size increase is small: averaging an extra half student in elementary classes, and one student in upper grades. To put this in perspective, a snow day would likely take a larger toll on most students.

Paradoxically, increasing class size, if coupled with smart teacher-assignment policies, may make students better off while simultaneously reducing costs. Here’s how: as studies show, having a good teacher trumps the class size effect. Class sizes would have to fall by at least 10 students to make up for having an average teacher instead of a crackerjack teacher.

Typically, kids are distributed more or less evenly so all classes are about the same size. But if that seems fair to the teachers, think twice about whether it works for the greatest number of kids. Why should only 25 percent of students get the top 25 percent of teachers? Wouldn’t tucking a few more kids under the wings of the best teachers and fewer in weaker teachers’ classrooms be better?

My research, which simulates gains in 5^th and 8^th grade students’ test scores using data from North Carolina, has found that 8^th graders could gain the equivalent of almost two weeks of learning in math and science if up to six additional students were shifted from weaker teachers’ classes and placed into the most effective teachers’ classes. For 5^th graders, learning gains were more modest, but access to the best teachers still delivers better results than equal access to all.

Of course, we’d want to pay our best teachers for taking on larger classes. Instead of using the funds saved from the staffing cuts exclusively for overall salary increases, as Superintendent Garza proposes, why not mainly up the pay for teachers who take on more students? That way, Fairfax County would be more likely to hang on to its best teachers, too.

So, let’s get over our obsession with class size and look hard at what can be done amid a real financial crisis. Research suggests that the smart money will be on rewarding and keeping our best teachers and thinking creatively about how increases in class size can help do that. As painful as downsizing the teaching force can be, it’s not as unkind as losing the best teachers would be.

Michael Hansen is presenting the findings of his paper, Right-Sizing the Classroom: Making the Most of Great Teachers, at an upcoming panel discussion co-hosted by AIR and the Thomas B. Fordham Institute. Click here for more details and to register.