Parents can create such incentives by exercising school choices informed by test results. Alternatively, a state can create a system of penalties or rewards for schools. School choice, however, is rare, and reward systems are hard to construct. I was wrong. Not only had I underestimated how much schools would improve to avoid being exposed, but I had not realized how inexpensive testing is.
Testing is undoubtedly the school reform with the highest ratio of benefits to costs.
We could reduce class size by two-thousandths of a student. While incumbent teachers would not mind a raise, such a tiny increase will not draw talented people into teaching or retain a teacher with good outside job opportunities. You could keep students off the streets and involved in after-school activities for almost two hours per year , assuming that the activities are cheap. Although children need after-school supervision and stimulation, part of one afternoon will not help much. To be fair, the child will be in twelve grades that use standardized tests before he reaches college, so you could add up the cost over those twelve years.