74 Interview: Educator & Khan Academy Founder Sal Khan on COVID’s Staggering Math Toll

After the release of NAEP revealed the worst-ever decline in math scores, the Khan Academy founder is sounding the alarm

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See previous 74 Interviews: Economist Tom Kane on the challenge of reversing learning loss, education researcher Martin West on this fall’s NAEP results, and journalist Anya Kamenetz on what COVID took from a generation of American students. The full archive is here

By some measures, Sal Khan is the most influential math teacher in U.S. history.

The 46-year-old entrepreneur and former financial analyst is the founder of Khan Academy, a nonprofit site offering thousands of free video lessons on a range of K-12 subjects. Since its beginnings as a YouTube channel (which itself grew out of Khan’s early efforts to tutor his niece in math), the organization has blossomed into an internationally known learning tool reaching tens of millions students in over 100 countries. Among its English-speaking users, Khan’s gently probing voice has become the soundtrack to their efforts to learn algebra or geometry.

The organization’s mission grew during the pandemic, as traffic to the website surged amid widespread school closures. User minutes on the site grew steadily in 2020 while American students were largely learning in isolation from teachers and peers, and for a time, school systems across the country were attempting to recreate Khan Academy’s model on the fly.

Their efforts, while often heroic, were insufficient. Reams of COVID-era research have shown conclusively that remote instruction led to disastrous learning losses in foundational subjects, with particularly steep declines in math skills. And even after two years of doleful news about schools and learning, October’s release of NAEP results still managed to shock education observers.

The federal test, often called the “Nation’s Report Card,” showed that fourth and eighth graders both sustained unprecedented drops in math performance. The damage to older students was especially severe, with 38 percent of eighth graders scoring below the exam’s lowest level of proficiency during the 2021–22 school year. While the worst of the pandemic-related learning disruptions is behind us, a long climb remains ahead.

In an interview with The 74, Khan said that learning recovery can’t stop with a return to the pre-pandemic norm, which saw huge numbers of students ill-prepared for college and bound for frustrating bouts with remedial coursework. He believes that American math education should be more organized around the principles of “mastery learning,” a pedagogical strategy that focuses heavily on providing pupils the necessary support to address their existing knowledge gaps before moving on to new material.

Failing a shift toward more effective math instruction, he argued, the damage revealed by October’s NAEP scores will result in lasting harm to students’ prospects in life — and it won’t be distributed equally.

“My kids are doing just fine, and everyone in their school is doing fine,” Khan said. “But somebody else’s kid is on the other end of that average, doing pretty darn badly and probably unable to compete.”

This conversation has been edited for length and clarity.

The 74: What are your thoughts on the huge declines in math performance revealed by NAEP? Is this roughly what you were expecting, given the effects of COVID?

Sal Khan: My big takeaways are that it’s not surprising that the drops were larger in math, and it’s not surprising that they were larger in eighth grade than in fourth grade. We always talk about how math is cumulative — if you start having gaps earlier on in math, it becomes that much harder to even engage later on. Gaps obviously matter in reading comprehension, and you want a strong foundation, but you can still engage later on if you fall behind.

The silver lining on these results is that they put a spotlight on what’s happened, but it’s not as if scores went from decent to bad; they went from horrible to even-more-horrible. Pre-pandemic, about one-third of eighth-graders were proficient in math, and now one-fourth are proficient. And it’s actually worse than that in some of the large urban districts that we know need a lot of help. Detroit Public Schools went from [5 percent of eighth-graders being proficient in math to 4 percent]. If I looked up where I live — Mountain View, California, or Palo Alto Unified School District — I’m guessing those numbers are closer to 80 or 90 percent proficiency. So even though the averages are pretty bad, they also hide the problem.

The idea of math as a uniquely cumulative subject is one you hear a lot about. Can you explain how that works in greater detail?

In education, memorization and math facts are kind of nasty words, but I definitely believe that fluency is valuable. So I’ll talk about it on a theoretical level.

Say you’re a little shaky on what seven plus seven is, and you have to count on your fingers. Then you move on to multiplication, which is basically repeated addition: seven plus seven plus seven. If you have to compute those things and don’t know off the bat that seven plus seven equals 14, you’re not going to get the multiplication fluency either. All of a sudden, you start doing word problems or exponents, and you’re going to be in a lot of trouble. And this keeps happening! If you get a 70 percent on your negative numbers test, you’re going to be adding fractions with negative numbers next, and you might not even get a 70 on that test. So you compound these gaps, and of course it will eventually fail. The way I usually talk about it is with a homebuilding analogy, where if you have a weak foundation, what you build on top of it will collapse. 

This isn’t a crazy theory. I visited a school in the Bronx a few months ago, and they were working on exponent properties like: two cubed, to the seventh power. So, you multiply the exponents, and it would be two to 21st power. But the kids would get out the calculator to find out three times seven. They knew what to do, but the fluency gap was adding to the cognitive load, taking more time, and making things much more complex. And if you get to an algebraic equation where you have to get that in several steps — and God forbid someone says you can’t use a calculator because it’s just simple multiplication — it just gets harder and harder.

Put the NAEP data aside. Maybe 50 or 60 percent of American kids try to go to college, and of those who do, the majority are placed in remedial math — which is not high school math, it’s like seventh-grade math. Even college algebra is really a remedial class, essentially tenth- or eleventh-grade math, and most kids can’t place into college algebra. It shows you how they slow down around that point, and in my mind, it’s because of these gaps.

Remedial math is also kind of the kiss of death in terms of college completion, right?

Exactly. This is a whole other conversation, but we have a program with Howard University where students in Title I high schools can get mastery in college algebra on Khan Academy, and then Howard University gives them transferable college credits for the subject. That’s one of the ways we think we can get people back on track. 

Another idea that circulated after the NAEP release was that eighth-grade math is a kind of gateway to more sophisticated academic concepts, making it an especially bad year to see reversals. 

Actually, they’re both interesting years. Fourth graders are starting to integrate a lot of the arithmetic they’ve learned up to that point, and in eighth grade, you’re combining the arithmetic with pre-algebra and starting on algebraic material. The eighth-grade Common Core standards are essentially Algebra I, and Algebra I is the most popular course on Khan Academy. It’s not surprising to me because that’s where people start hitting walls.

Why? Because it’s a new way of thinking about math. But for most people, it’s because their fluency in pre-algebraic or even arithmetic-level skills is pretty weak. If you look at the curve in the national data, kids fall further and further behind relative to where they should be, year in and year out. And when students are able to do personalized practice and address their unfinished learning, it doesn’t seem like a coincidence that eighth grade is also when students see the biggest, most dramatic gains in math.

Algebra I is the most popular course offered by Khan Academy, founder Sal Khan observed. (Nikolas Kokovlis/Getty Images)

You mentioned that memorization is sort of a nasty word. But I think many people experience a bit of success with that in the early years of math, with the multiplication tables offering one example. Do you think there’s room for more of that in K-12 math — perhaps through methods like direct instruction, which places a lot of emphasis on explicit teaching methods and systematic lessons?

Yeah, although I’m actually a little bit allergic to direct instruction. I’m the chairman of two schools that I started, and for high schoolers, I think there should be no lecturing at our schools. You should be asking questions, making the students think about things, making them collaborate. With younger kids, of course there’s going to be more direction there, but it still shouldn’t really be a lecture. I think that’s really important, especially for young kids. What we call play, that’s really children exploring so that they can learn about the world. Kids love to explore and do things; they don’t love to sit in the chair with their fingers on their lips and learn to be docile. 

In the math wars, there’s the rote learning and memorization, whatever you want to call it, and there are higher-order skills and problem solving. I absolutely think it’s got to be both. Schools that only do the latter, like project-based learning schools, their kids still struggle to get engineering degrees even though they were potentially doing engineering-type lessons during high school. Because they didn’t learn fluency in some of the core skills! Meanwhile, I know plenty of people who went through traditional education systems that might have leaned a little bit towards rote learning — especially in other countries like India and China and Korea — and I don’t think that’s ideal either. But you do have to get the core fluencies before you get too conceptual, in many cases, and advocates of more progressive education don’t necessarily buy into that.

Those eighth-graders I met in the Bronx were not atypical. I just wanted to sit down with them for like 24 hours and make sure they could nail their multiplication tables. Some people think that if you make them memorize the multiplication tables, they won’t know what multiplication is. No, they understand the concepts, and they know what multiplication is. But can you imagine going through life saying, “I don’t know what three times seven is”? It’s actually a problem if you see a pair of pants that costs $70, but they’re on sale for 30 percent off, and you can’t figure out that you can save $21. You’re going to be in trouble. So I do think that math facts shouldn’t be a forbidden concept, but that doesn’t mean you shouldn’t also do conceptual learning.

I feel the same way about history. When people say that kids can just Google things, I think, “I don’t know, it’s pretty useful for me to know when World War II was.” These are things that shouldn’t be in competition with one another.

You used the phrase “math wars,” and I’m wondering how much those are truly being fought. What we called the reading wars were really destructive, but also constructive in that they’ve produced a huge research literature about how to teach literacy. Does it strike you that the math world hasn’t really been through the same process, and that the “science of math” is therefore something of a mystery to both educators and kids?

Yes and no. The reading wars were whole-language vs. phonetics, and again, I think the answer is both: You probably start with phonics and move more toward whole-language as kids get older. You don’t need to fight these wars. 

It’s not like there aren’t already cases of kids learning math really well. There are lots. We started talking about how math is cumulative, and the strongest evidence for that — from well before Khan Academy existed — is around the notion of mastery learning, which always gives students the opportunity and incentive to fill in any gaps they have. And it’s had something like 200 efficacy studies, all of which were dramatic in terms of what they found for student learning. That’s essentially the pedagogical underpinnings that we’ve used; we’ve had 50-plus efficacy studies of Khan Academy, and they all have the exact same narrative.

So I don’t think it’s a secret of what we should do. The kids at KLS [Khan Lab School] — and they’re not indicative of a historically under-resourced community, it’s in the middle of Silicon Valley — are growing 1.5–2 times faster in math than demographically comparable kids in local public schools. That’s because they’re doing mastery learning, and they’re doing some things in peer-to-peer and active learning that are contributing as well. I think if you let kids work in their zone of proximal development, and you motivate them, you can actually accelerate people in math pretty quickly.

What about the long-term trends in American math results? Last year’s NAEP release shows pretty clearly that, even though we’ve stagnated or declined recently, we’re still quite far ahead — in some states, massively so — compared with the early 1990s. Do you think that’s a meaningful thing to keep in mind?

The long-term trends have definitely been positive. There has been progress, for sure, and I think that a lot of that has come from things like desegregating schools. When I was growing up in New Orleans, there were public schools that didn’t have air conditioners. These were the legacy schools from Jim Crow, so I think a lot of that progress is probably basic blocking and tackling, just having some level of equality before you even start talking about equity.

And there has been improvement in teaching as well. I believe it’s now mainstream for teachers to say, “I’m not going to just lecture at my students for an hour.” It’s far more typical now, compared with when you and I went to school, for the math teacher to give a short lecture and then break the class into groups to solve problems together. But the fact remains that it’s a disaster when only one-third of kids are proficient in math and a majority of kids going to college need math remediation at something like the seventh-grade level. 

Post-pandemic, the rate of learning might get back to where it was pre-pandemic. But it just means that you’ve been set back by 15 or 20 percent, at least, and now you’re going to continue to learn at that suboptimal rate. The average American kid learns at about .7 grade levels per year, and that accumulates to the point where lots of high school seniors are closer to the seventh-grade level than the twelfth-grade level. Which, again, is exactly what the college remediation numbers show. 

It’s a huge problem, and it’s hugely unequal. My kids are doing just fine, and everyone in their school is doing fine. But somebody else’s kid is on the other end of that average, doing pretty darn badly and probably unable to compete.

The NAEP results showed that almost 40 percent of American eighth graders scored below the test’s most basic proficiency level. What does it mean to be an adult with only the most rudimentary math skills? 

That 40 percent is going to be sitting in classrooms, getting more and more frustrated and continuing to think they’re not smart. 

And the people around them are also going to think they’re not smart. Imagine you’re a well-intentioned teacher thinking that you’re explaining ninth-grade math just fine, and this kid just doesn’t get it. By that point, there are going to be two problems: One, they have all these gaps that are hard for you, as a ninth-grade teacher, to address. And two, their self-esteem is shot, and they’re checked out. Some of these kids are going to drop out of high school, not even think about college, and be that much less likely to have a good path in front of them. It’s not a good scenario. 

I remember reading one account, though I’m not sure how true it is, that because the lead time in prison planning is around 10 years, the authorities would look at fourth-grade test scores to correlate the planning. That’s about the darkest idea you can imagine, but it’s not crazy. Prison is obviously an extreme circumstance, but dropping out of high school, or dropping out of college with debt, is where a lot of these kids are headed.

You may have also seen the research showing that, based on previous data tracking math scores and economic trends, a permanent drop in NAEP performance of this magnitude could erase something like $900 billion in future earnings.

And remember that it will disproportionately hit certain student demographics. If it were my child that fell into that “below basic” category, my wife or I would probably quit our day jobs. Knowing what I know about the system and its implications, and given that we have the resources, I would go all-in to help my kids catch up. And we’re talking about 30 or 40 percent of the country. 

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