Given the challenges facing American public education today, identifying effective teachers is a more vital task than ever before. In the U.S. public school system today, the method used to determine teacher effectiveness--and thus to drive salary, promotion, and tenure decisions--is based on a few external credentials: certification, advanced…

Paying teachers varying amounts on the basis of how well their students perform is an idea that has been winning increasing support, both in the United States and abroad, and many school systems have adopted some version of it. Proponents claim that linking teacher pay to student performance is a powerful way to encourage talented and highly…