From the Gates Foundation 2012 Annual Letter:
I still find it hard to believe that 95 percent of teachers are not given specific feedback about how to improve. Even more important than a pay schedule that rewards excellence is identifying and understanding excellence so that teachers know how they can improve. In all the meetings I have had with teachers around the country, and in the surveys we have done, it is clear that most teachers want more feedback and will use it to improve, even if the financial rewards for performance are comparatively modest.