These regulations are always couched in terms of assuring teaching quality. Only with strict standards, we are told, can we be confident that the best teachers are in our children's classrooms. The American Federation of Teachers (AFT) has recently taken this view to an extreme, calling for a new "bar exam" for teachers. Its recent report, "Raising the Bar," argues that "teaching must raise standards for entry into the profession through a process similar to the bar process in law or the board process in medicine."
It's not surprising that the AFT would endorse such onerous entry requirements. Limiting entry into the profession means less competition for current teachers -- and maybe even a profession-wide pay increase, if schools begin struggling to find applicants willing to jump through all of the new hoops.
Nonetheless, it seems hard to dislike the AFT's idea at first blush. After all, won't the bar exam help ensure we get the smartest and most qualified teachers? Even Joel Klein, an enterprising reformer when he was school chancellor in New York City, has fallen for this view.
But it's wrong. This rationale fails for two main reasons.
First, barriers to entry deter people from pursuing teaching in the first place. We have already discussed Bill the engineer, for whom becoming a teacher would require a commitment so time-consuming and expensive that it's hard to believe it would be worth his effort. A bar exam for teachers would likely discourage him even more.
And it's not just mid-career professionals like Bill who are deterred by onerous licensure requirements. High-ability college students must sacrifice time spent studying math and science in order to take required education courses and bone up on the latest trends in pedagogy. Smart students on the fence about whether they want to become teachers will likely choose the math and science courses (which have broad labor market value) rather than wasting time on education courses (which have value only if they pursue teaching).
The second reason a bar exam will not improve teacher quality is more fundamental: Scores on these tests are simply not good predictors of teacher effectiveness. In fact, economists and education scholars have known for decades that the standard resume characteristics -- level of education, certifications or licenses, and experience beyond the first few years of teaching -- have essentially zero power to predict how much students learn from a given teacher. Even raw intellectual ability as measured by IQ tests has only a small positive effect on how much knowledge teachers are able to impart to their students.
To illustrate more vividly, a teacher with a doctorate degree, every certification and license available, and 15 years of experience is no more likely to be a high performer than a teacher with a B.A., the minimal certification, and five years of experience.
On reflection, this should not be too surprising. Clearly teachers need to be intelligent and knowledgeable, but effective teaching requires a rare blend of patience, empathy, articulation, and motivation -- qualities that cannot be easily measured on a bar exam or other standardized test.
For all of these reasons, a bar exam is not any more likely to put effective teachers in the classroom than existing certification tests are. This is especially true if the bar exam covers faddish pedagogical theories that often lack a scholarly foundation.
There is a better way to improve teacher quality. It's essentially the opposite approach of the one espoused by the AFT. School districts should be less discriminating in choosing new teachers, but more discriminating in deciding which veteran teachers receive tenure. This approach may seem counterintuitive, but for teachers, the best predictor of future results is past performance. Teachers who show strong performance -- as measured by student tests and principal evaluations -- should quickly move up the pay scale, while those who perform poorly should be let go or denied raises.
When economists Douglas O. Staiger and Jonah Rockoff simulated how this kind of system might work, they found that it would involve a rather high rate of turnover. In their view, only the top 20 percent or so who performed best during their tryout period should be kept on.
Whether Bill the engineer would make the cut is unknown. But lowering barriers to entry into the classroom would at least give him the incentive to try.