The Washington Post
“Education experts have long viewed teacher turnover as a negative factor that erodes student achievement and contributes to an unstable school environment. But a new study of IMPACT — the controversial D.C. Public Schools teacher evaluation system that has been accused of contributing to the city’s higher-than-average turnover — suggests that not all turnover is created equal.
The departure of teachers who score poorly on IMPACT is actually a good thing because student scores on math and reading tests tend to improve substantially after such teachers depart, according to a working paper to be published Monday by the National Bureau of Economic Research.”