Students achievement increased when ineffective teachers were asked to leave.
Schools across the country, especially those in low-income neighborhoods, struggle to recruit and retain teachers, an effort made more difficult by the nationwide teacher shortage and a dwindling number of people entering the profession.
A growing body of evidence shows that teacher turnover, especially the high turnover rates in many of the most underserved communities, reduces student achievement.
So why is one urban school system proactively asking teachers to leave?
As it turns out, increasing teacher turnover for the right reason, like eliminating bad teachers, can have a significant positive impact on student performance, at least in the nation's capital.
"Often when you look at teacher turnover we have this expectation that it's going to be something negative for students," says James Wyckoff, professor at the University of Virginia and an author of a new study on the impact of the District of Columbia's teacher evaluation system.