The "teacher effectiveness gap" was just a myth: 3 implications

CORRECTION. This fantastic Gotham
Schools article
explains that
New York’s rating system was designed to guarantee that “effective” and “ineffective”
teachers would be found all over the city. Which renders the New York Times story—and my post—basically
moot.
Still, this wasn’t the first bit of evidence showing that we might not have a
teacher effectiveness gap, or at least much of one. This rigorous CALDER study, in particular, found that:

The
average effectiveness of teachers
in high-poverty schools is in general less than teachers in other schools, but
only slightly, and not in all comparisons. The authors also find differences in
within-school-type variation in teacher effectiveness in nearly
every comparison. These differences are largely driven by the longer tail at
the bottom of the teacher effectiveness
distribution in high-poverty schools. Teachers at the top of the effectiveness
distribution are very similar across school settings.

So the evidence on the lack of a gap isn’t as open and shut
as my post implies. But it certainly appears likely that the gap is much
smaller than we once thought—which does call for pushing the pause button on
massive efforts to move teachers around.

***

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?

We can take "closing the teacher effectiveness
gap" off our to-do list.

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.

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