Teachers have a lesson for business leaders about how to improve their worst performers

U.S. businesses spent $71 billion training their employees last year. Perhaps they could have kept some of that cash.

New research on boosting teacher performance suggests one of the most effective methods of improving a workforce may also be the cheapest: pairing a firm’s weakest employees with its strongest and asking them to bring the lower performer up to speed.

To test the theory, a team of researchers from Brown and Harvard conducted an experiment with 136 teachers at 14 public schools in Tennessee. (Tennessee was selected, in part, because it measures teachers on 19 separate skill areas, from managing behavior to asking questions.)

Principals matched the school’s highest-performing teachers in some areas with their lowest performers in some of the same areas. The principals explicitly asked the pairs to work together to help the weaker partner improve over the year.

The resulting gains in teacher performance, as measured by student test scores, were “meaningful,” according to a working paper recently released by the National Bureau of Economic Research.

The researchers reported that students of lower-performing teachers who took part in the study saw their test scores rise by nearly one standard deviation, compared to similar students in classes where the teacher didn’t take part in the program. The scale of the improvements are roughly akin to the difference in the value between a novice teacher and a veteran with five to 10 years of experience.

While the Tennessee study was limited to teachers, the underlying idea—pairing high and low performers—would make sense in lots of work places, Eric Taylor, one of the researchers, told Quartz. The one caveat, he said, is that teachers may be different from other workers in that they are notoriously isolated from one another.

In other words, in many businesses, employees may already be learning from their peers, which could reduce any potential gains from pairing high-performing and low-performing workers. Still, firms that depend on somewhat isolated individual workers, such as far-flung salespeople or telecommuters, may benefit from such an approach.

Companies have incentives to experiment with different ways to develop their employees. Despite the huge sums companies pay on training, it’s less than clear how much how much it improves performance.

Laszlo Bock, Google’s head of HR, surveyed the academic literature for his 2015 book Work Rules!: Insights from Inside Google That Will Transform How You Live and Lead. Bock found experts believe as little as 5% of training is actually retained. That’s one reason Google invests more in hiring than in training, Bock wrote.

For companies looking for a more cost-effective way to help low-performing employees develop, the lesson of these Tennessee teachers might be worth a try.