Of teacher shortages and quality: now that we can identify good teachers, let's reward them.

Good teaching--the kind that can routinely raise student achievement--is the most valuable of all education resources. When a teacher inspires, children learn, even when the building is antiquated, the Internet is missing, and classes are bigger than usual.

So teacher quality matters. A lot. Yet the standard measure of quality today, the teaching credential or license, is no sign of quality. A man may carry a driver's license in his wallet, but that does not mean he will stay in his lane. Similarly, we are not guaranteed an effective teacher because of a license verifying that he or she has passed a batch of education-school courses and spent a few months practice-teaching.

Still, states continue to require one or another of literally dozens, even hundreds, of different education credentials for each and every subject. In the process they have managed to manufacture an apparent shortage of "qualified," that is, credentialed teachers. On this matter, Michael Podgursky ("Is There A 'Qualified Teacher' Shortage?," page 26) provides fascinating information from the state of Missouri.

All this focus on credentials obscures the genuine shortage of an adequate number of truly qualified teachers: those who can help students realize their full potential. By paying teachers according to their credentials and the number of years they have been on the payroll rather than how well their students perform, the rewards go to the credentialed careerist, not necessarily to the meritorious teacher. And when talent is not rewarded, talented people turn to other fields of endeavor, all the more so in an age when able women have many new career opportunities.

Attempts to introduce merit pay have been effectively thwarted by strenuous union opposition. Unions argue that one cannot easily distinguish between a good teacher and a bad one. While that may once have been the case, many districts and states are now collecting information on student performance in such a way that principals and superintendents can track how much a given child is learning from one year to the next, and from one teacher to the next.

That information can be a powerful tool for identifying effective teachers. Brian Jacob and Lars Lefgren ("When Principals Rate Teachers," page 58) show that teachers that were effective with last year's class will tend to be effective this year as well. By the same token, teachers who have never been effective are not likely to become so. To those who remember the great teachers they had in school, the finding may appear obvious. It is all the more distressing that teacher pay schedules ignore it.

The Jacob-Lefgren study also shows that school principals are good at identifying the very best teachers as well as the weakest ones, exactly the capability needed to reward the topflyers while weeding out those who belong in another profession.

To its credit, as William Boyd and Jillian Reese tell us in their feature essay ("Great Expectations," page 50), the National Board for Professional Teaching Standards (NBPTS) has tried to enhance teacher quality. And the certification process seems to be able at least to identify more effective teachers. Perhaps NBPTS-certified teachers deserve an extra reward, if they go to the effort of applying for and then actually passing their "boards." But so far, the jury is still out on whether the program helps create good teachers or simply spots the existing ones.

The solution to the so-called shortage of qualified teachers may well lie with more commonsensical solutions. Let principals, themselves to be chosen for their effectiveness, recruit, reward, and retain the truly qualified teachers. That is no different from the personnel policies followed by successful firms in competitive industries.

Once talented teachers are so recognized--and paid according to their effectiveness--there is no reason not to compensate them a lot better than they are today. It is true that teachers' weekly compensation packages are, on average, often better than in other professions. But students could learn a lot more, and teachers could be paid a lot more, if schools paid bigger salaries to the best and the brightest, but not to the ineffective.