As I noted this morning, the National Education Association has come up with a not-so-modest proposal purportedly aimed at reducing the high school dropout rate: raising the age at which it is legal to leave high school to 21.

Wouldn’t it be preferable to beef up the quality of instruction? Since forty-seven percent of the nation's drop outs say they left because they were bored, and forty-five percent said they didn't go on because they had been prepared poorly in the lower grades, according to a Gates Foundation study, why not enrich instruction instead of just forcing potential dropouts to sit around in class a few more years?

Since I had already been thinking about this issue, I was delighted to happen upon a story (“How’s My Teaching?”) in City Journal about innovations in the ways public school teachers are being evaluated in several school districts. These evaluations, in turn, affect their pay. New York mayor Michael Bloomberg, New York governor Andrew Cuomo, and New Jersey governor Chris Christie are among the latest prominent policymakers to embrace innovative ways to evaluate teachers.

As somebody who still counts some really wonderful teachers high-school teachers as prime influences in my life, I wholeheartedly agreed with this point in the article:  

[F]or an individual student, the difference between being assigned to one or another teacher can mean as much as a grade level’s worth of learning during the school year.

Further, recent research by economists at Harvard and Columbia shows that teachers influence their students later in life: being assigned, that is, to an effective versus a less effective teacher has a bearing on the likelihood of teen pregnancy, on the probability that a student goes to college, and on students’ earnings as adults.

The enormous disparity between the best and worst teachers indicates that the current system does a poor job of ensuring teacher quality.

The current system of rewarding teachers is based on credentials, and those credentials are derived from education courses. A high school history teacher, under this system, may not recognize the name Thucydides, but she’s had plenty of education courses, the more education courses the better her pay is likely to be.

The assumption underlying this system of rewards is that teachers who took similar professional courses will be similar in their teaching skills. No need, really, to do any serious, on the spot evaluation. Indeed, an astonishingly high percentage (98!) of public school teachers do get positive evaluations. But author Marcus Winter writes:  

The problem, however, is that over the last two decades, empirical research has revealed that teacher quality does in fact vary substantially, not only across but within public schools.

Getting a master’s degree in education has no effect on how successful one will be as a teacher, Winters observes, though the degree may net a better salary than that of somebody who has taken fewer education courses. The new way is different:

Rather than screening teachers before they’re hired and then assuming that they’re performing well, the new strategy focuses on distinguishing between the best and worst teachers by assessing their actual classroom performance….

The recent movement to revamp teacher evaluations could bring us closer to the day when all public school students have the chance to be taught by high-quality teachers.

Why do I think the NEA isn’t going to like this idea any better than it likes school vouchers?