Yes, Upward Mobility is Possible
DeBoer’s second key contention—that even effective interventions cannot narrow achievement gaps despite increasing average performance—is similarly misguided.
Although test scores in early grades do strongly predict future achievement and attainment, there is “statistically and economically significant variance in upward [achievement] mobility across districts,” according to one recent analysis examining 3 million students. Most disturbingly, such upward mobility is especially rare in districts serving disadvantaged students—the very students who begin school farthest behind academically and who most desperately need high-quality schools and compensatory interventions.
Recent national trends also demonstrate that achievement gaps are not fixed. When NAEP scores were improving in the 1990s and the early 2000s, the gains were driven disproportionately by the lowest-achieving students. Over the past decade, the observed decline has occurred almost exclusively among low performers. As the American Enterprise Institute’s Nat Malkus has put it, “the bottom is falling out.”
There are two reasons we should expect students at the bottom of the achievement distribution to be most sensitive to education policies. The first is that many interventions are intentionally targeted toward struggling students. If effective, they’ll narrow achievement gaps by design, because high-performing students won’t get them. The second is that disadvantaged students most need high-quality schools to compensate for disadvantages they face outside of the classroom. Higher-income students are more likely to have plenty of support at home, and their parents have the resources to compensate for bad schools.
So, if we find the right interventions and intentionally target the students who need them most, how much relative growth is possible? In her analysis of New York City charter schools using randomized admission lotteries, economist Carolyn Hoxby benchmarked her results against the observed achievement gaps between Harlem, a low-income Black neighborhood, and Scarsdale, one of the most exclusive and affluent suburbs in New York. Attending a New York charter school from kindergarten through 8th grade, Hoxby found, closed 86 percent of the “Scarsdale-Harlem achievement gap” in math and 66 percent of the gap in reading.
To be sure, New York is exceptional in many ways. Charter schools are a mixed bag nationally, as deBoer has noted, though they have improved in recent years. But the source of this variation is important. One reason why charter schools seem to produce more positive effects in urban areas than in higher-income suburbs is because of the differences in the quality of the existing non-charter options. Such variation in impacts is precisely what we might hope to see if our goal was to narrow opportunity gaps and improve educational opportunities for kids currently left behind.
One of the most effective spokesmen for the idea that education interventions can help students at the bottom of the achievement distribution—and thus close achievement gaps—is once again deBoer himself. When Kelsey Piper and Karen Vaites wrote a persuasive rebuttal to his trashing of the “Southern Surge,” deBoer penned a rejoinder conceding that phonics-based reading instruction does indeed work—but better for some students than others.
“Many studies show that the biggest gains from phonics are for the weakest readers, or those behind in fluency or decoding,” he summarized. “(This is also true in math and all manner of other domains btw.) Children who already have decent oral vocabulary, background knowledge, home reading, etc., often get less additional benefit.”
Exactly.
