Rating New York City's Teachers

We have all heard new stories where teachers were accused of helping students cheat on test scores. Well what do you think some teachers might do if their performance was put under a microscope based on student's test scores? That is exactly the problem that New York City's teachers will be facing:

New York City has embarked on an ambitious experiment, yet to be announced, in which some 2,500 teachers are being measured on how much their students improve on annual standardized tests.

While officials say it is too early to determine how they will use the data, which is already being collected, they say it could eventually be used to help make decisions on teacher tenure or as a significant element in performance evaluations and bonuses. And they hold out the possibility that the ratings for individual teachers could be made public.

I am not suggesting that these teachers would do anything unscrupulous, I am merely stating that the temptation is there.