“We’re on the right track,” she said. That was also the conclusion of researchers from Stanford University and the University of Virginia who examined how the system evaluates teachers. Their study, published as a working paper of the National Bureau of Economic Research, found that the IMPACT system put in place in 2009, with its controversial combination of big rewards and serious accountability, has resulted in low-performing teachers leaving the system. Equally significant was the finding that those who stayed – teachers with both strong and weak scores initially &n...