The “Teacher Effectiveness Gap” Was Just a Myth: Three Implications by Michael Petrilli

The finding—reported by the Times this weekend—that really good, and really bad, teachers are evenly distributed around New York City is jaw-dropping news. It upends everything we thought we knew about teacher quality, especially the notion that our achievement gap is caused in large part by a “teacher quality gap,” with the worst teachers clustered in the neediest schools. But they aren’t. So now what?

Let me stipulate that this finding might be incorrect (though previous analyses have come to similar conclusions). Maybe it’s harder for teachers in affluent schools to show strong value-added gains, because their students are already topping out on the tests. Perhaps student mobility is making teachers in high-poverty schools look better than they really are. (Their worst students don’t show up for testing—or have already moved onto another school.)

But assume it’s true. What are the implications?

• Affluent schools are spending more for their teachers—but they aren’t getting better results. We know from research by Marguerite Roza and others that low-poverty schools tend to employ older, and thus more expensive, teachers than their poorer counterparts. We all know the system features that enable this to happen—seniority bumping rights, a single salary schedule, etc. But these older, more expensive teachers aren’t getting stronger value-added gains than their younger, less expensive peers. This is more evidence that the teacher qualifications we can measure (and for which our salary schedule pays extra)—degrees, years of experience, etc.—are not related to effectiveness.
• Affluent schools might be getting less value added by choice. It’s perfectly reasonable for educators and parents in affluent, high-achieving schools to trade-off sky-high math and reading scores (and/or test score gains) for other values, like more time for art, music, science, history, and P.E.
• A focus on “redistributing effective teachers” from affluent to poor schools seems misguided, or worse. It turns out that effective (and ineffective) teachers are everywhere. Which means that we should push the pause button on efforts to move teachers from one kind of school to another—efforts that many reform groups want embedded in the next Elementary and Secondary Education Act.

We have a lot of problems in k-12 education to address. Let’s be grateful that we can take “closing the teacher effectiveness gap” off our to-do list.

-Mike Petrilli