As a business leader, what do you do with the weakest performers on your team? One option, of course, is to let them go. Often that's the right answer. But what if an employee is great in one key area, but terrible in another? Or that person has a hard to hire for skill you desperately need? Or the individual is clearly talented but lacks the structure and experience to put their abilities to the best use?

The standard answer then is train them, but there are at least two big difficulties with traditional training. One is it's often pretty expensive, and two training generally doesn't work all that well. The American Society for Training and Development itself says that 90 percent of what employees learn during training isn't retained.

Maybe you already employ the best trainers around?

So what's a better alternative to expensive and unreliable training staples like workshops and webinars? Quartz writer Oliver Staley thinks he's found a possibility in recent research on teachers.

A new study conducted in Tennessee, he reports, found a way to boost teacher performance that is both cheap and effective -- simply pair up low performers with super stars for coaching. "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," Staley notes.

Which is obviously fascinating if you work in the field of education, but Staley spoke with Eric Taylor, one of the researchers behind the study, and he claims the results may be more broadly applicable in other industries.

Of course, if your top performers and weakest team members are already working together closely, you obviously have little to gain from pairing them up. But "firms that depend on somewhat isolated individual workers, such as far-flung salespeople or telecommuters, may benefit from such an approach," Staley reports.

Given that the only cost to you is the lost productivity of those top team members who devote some of their time to coaching (offset slightly by the increased performance of their mentees), pairing up your worst and best employees might be worth a try. After all, Google, which is famed for its effective, data-driven HR practices, already does something similar according to its SVP of people operations Laszlo Bock. The company utilizes its top employees as free in-house trainers to help bring poorer performers up to speed.