How can we fix well-documented disparities in the education experiences of children living in poverty? Don't leave the quality of their teachers up to chance—especially since state laws, union agreements, and pay systems all increase the odds that great teachers won't end up in schools serving disadvantaged students.

With Tennessee schools as the backdrop, a study by Walker Swain (University of Georgia), Luis Rodriguez (New York University), and Matthew Springer (University of North Carolina - Chapel Hill) examines a short-lived experiment with teacher retention bonuses. Unlike bonus systems in other districts that are quality-blind (like the high-need schools bonuses in Denver) and offer smaller dollar amounts (such as $1,000 in Cleveland or $2,000 in San Francisco), the state paid out decent $5,000 bonuses to teachers who were willing to work in the toughest schools, but only if they had earned top evaluation ratings.

Did it work? In short: yes. Did it last? No.

The researchers found evidence that participation in the bonus program led to modest improvements in student test scores in math, and better still in reading achievement—benefits that persisted after the incentive system was terminated.

Because the experiment was funded using federal Race to the Top funds, the program abruptly ended when that well dried up. Here's hoping the Tennessee legislature revisits that decision.