In effect, this deal undoes a central - and in my opinion, unfortunate - component of weighted student funding, through which it costs principals more to hire an experienced teacher than an inexperienced one. Without a doubt, experienced teachers have been remaining in the pool longer than their less experienced counterparts. What the union and the DOE have debated is whether this is a cost issue or a quality issue. Some figures from the original New Teacher Project report: Because of seniority rules, 44% of teachers excessed in 2006 had 0-3 years experience, while 22% of teachers in this pool had 13+ years of experience. Of the 235 teachers who remained unplaced as of December 2007, only 25% of these teachers had 0-3 years of experience, while 42% had 13+ years of experience. (See graph below.)
Now we'll have a strong test of the claim that these are "bad teachers" that no principal wants to hire. But beyond the ATR issue, it's worth thinking about how the deal - and principals' reactions to it - may affect the future of teacher price incentives in New York City and beyond. Sure, experienced teachers should be more evenly distributed across schools, but I've never seen any evidence that making principals pay more for them is going to achieve that outcome. In the worst case scenario, we end up with a tragedy of the commons dilemma in which individual principals, each acting in their own short-term interest, end up turning experienced teachers away from their schools, and the collective impact is to push them out of the district altogether.