Jill Barshay of the Washington Monthly is disappointed with the performance of our high school seniors on the latest NAEP results:

When you look at top achieving students in the top 75th and 90th percentiles. Their scores are FLAT. … High achieving students aren’t improving at all. So you can’t blame the infusion of more low performing students in the testing pool for the disappointing test scores. Even if we hadn’t introduced a greater number of weaker students into the mix, the scores of our high school students would still be stagnant.

Indeed, when you drill down by percentile, it’s the weakest students who are showing modest improvements. If not for their improvements, the national average would have declined!

I understand being somewhat surprised by the weakest students improving, given the way in which these students tend to have the deck stacked against them, whether thanks to poverty, unstable homes, unsafe neighborhoods, lack of school resources and funding, or developmental and cognitive disabilities. (Despite what many people assume, many or most special education students participate in the same standardized tests as their peers in mainstream education.) But it’s worth saying that, in many types of human achievement, it’s natural to expect those at the bottom to improve the most, as they have the most room to improve. Meanwhile, stagnant performance at the top should never really surprise us, as there are likely ceiling effects at play– students reaching the peak of their potential ability, whatever the admixture of demographic, economic, parental, and “natural talent” factors are at play. (And let’s not forget a frequently forgotten aspect of educational outcomes, random variation and chance.)

Why doesn’t Barshay consider this possibility? Well, I’m not sure. The culture of our educational conversation is clear enough: that talk of individual limits to ability for students, limits that cannot be changed by schools and teachers, is verboten. But we have every reason to believe that human beings are of substantially unequal academic ability, and that is especially true if we insist on assessing them primarily with the limited and reductive instruments of standardized tests, rather than taking a holistic view of their emotional, social, and creative intelligence. Everybody can learn. Whether everybody can grow on tests like the NAEP is a different question entirely.