Soon after, however, opportunities for smart women began to multiply. The Equal Pay Act of 1963 and the Civil Rights Act of 1964 were contributing factors, as was the societal shift in the perception of women's roles. As more girls went off to college, more women emerged ready to join the workforce, especially in the desirable professions that had been largely off-limits: law, medicine, business, finance, and so on. (One of the unsung heroes of this revolution was the widespread use of baby formula, which allowed new mothers to get right back to work.)So there is a whole standard deviation shift leftward (lowering) of teacher IQ as a consequence of opening opportunity to everyone. That is not an argument for returning to more limited horizons but it is a call to recognize the complexity of the issue and the trade-offs that are involved. This is especially the case given other research regarding teacher effectiveness. I do not have the studies at hand but my recollection is that a top quintile teacher advances their students by a whole year's worth of extra learning over a middle quintile teacher. If you lose half your top quintile teachers and double your worst performers, it is easy to see the compound effect of that standard deviation leftward shift.
These demanding, competitive professions offered high wages and attracted the best and brightest women available. No doubt many of these women would have become schoolteachers had they been born a generation earlier.
But they didn't. As a consequence, the schoolteacher corps began to experience a brain drain. In 1960, about 40 percent of female teachers scored in the top quintile of IQ and other aptitude tests, with only 8 percent in the bottom. Twenty years later, fewer than half as many were in the top quintile, with more than twice as many in the bottom. It hardly helped that teachers' wages were falling significantly in relation to other jobs. "The quality of teachers has been declining for decades," the chancellor of New York City's public schools declared in 2000, "and no one wants to talk about it."
This isn't to say that there aren't still a lot of great teachers. Of course there are. But overall teacher skill declined during these years, and with it the quality of classroom instruction. Between 1967 and 1980, U.S. test scores fell by about 1.25 grade-level equivalents. The education researcher John Bishop called this decline "historically unprecedented," arguing that it put a serious drag on national productivity that would continue well into the twenty-first century.
The complexity is also exemplified by the issue of absolute and relative wages, "teachers' wages were falling significantly in relation to other jobs." That statement is true. At the same time it is also true that teachers salaries have risen significantly in real financial terms over the years. In many parts of the country, a household that is headed by two working teachers, are in the 1% category. So compared to everyone else, teachers have done fantastically well on economic metrics but compared to the 0.1% they have experienced relative decline.