From a clip in the Memphis Commercial Appeal:
The retention bonus Tennessee offered last year to keep strong teachers in low-performing schools likely was a factor for more than 70 teachers who signed on for another year in inner-city schools, most of them in Memphis.
Of the 365 teachers that took the state up on the offer, 20 percent of them are more likely to have stayed compared to other high-performers not eligible for the incentive, according to a study by the Tennessee Consortium, an independent research body at Vanderbilt University.
“What does it mean that a better teacher is being retained? The average teacher was in the 89th percentile on the distribution in the state,” said Matt Springer, researcher. “The average teacher coming into priority schools is at the 25th percentile.”
For context, the gap in achievement between white and black students and those living in poverty, he said, would not exist if inner-city students could have the best teachers for five years. . . . .
Suggesting that all teachers could be in the 90th percentile of performance is the equivalent of suggesting that all players on a baseball team can bat .300. This ridiculous notion was first circulated by Bill Sanders of TVAAS infamy. Richard Rothstein lays this thought disorder to rest in his book, Class and Schools . . ., which remains an important read in understanding the relationship of economic class to achievement.
The other number that stands out in the Roberts piece is that 20 percent of teachers are more likely to stay. The other way of saying that is 80 percent of teachers receiving bonuses were no more likely to stay than those who were receiving bonuses.
The other big irony here is that the evaluation system used in Tennessee assures that many Level 5 teachers will become 2s and 3s by virtue of teaching in high poverty schools.