Some students were learning more math, before the pandemic, while most were learning less, writes Mike Goldstein. He believes changes in math teaching and the rise of private tutoring centers favor motivated students and those with motivated parents, explaining the K-shaped curve.
In the old days, a fourth-grade teacher would teach a lesson to all students, slowing the pace to keep stragglers from getting lost, and boring the advanced students. Over the last 10 years, he writes, it's much more common for elementary students to work independently on computers, while the teacher circulates.
"Evaluations tend to show gains for the more disciplined kids who actually do the math problems — but that, often, the typical student doesn’t do much."
In a 2018 study, California students who used Khan Academy for 30 minutes per week gained. But few students were that diligent. The majority did less than 15 minutes per week and made no gains, or lost ground.
Goldstein speculates that the software works for strong students, but isn't good enough to get struggling students "unstuck."
He also suspects that private tutoring centers, which have expanded in affluent communities, are contributing to gains for top-quartile students, who are more likely to have educated, motivated, well-off parents.
Where I live in Silicon Valley, there are tutoring centers everywhere -- nearly always with signs in Chinese on the windows.
People are trying to offer more tutoring in public schools, but "programs face significant operational obstacles," writes Goldstein. "Even programs that offer to make private tutoring free are under-used, like one in New Hampshire."