By Clive Thompson

Matthew Carpenter, age 10, has completed 642 inverse trigonometry problems at KhanAcademy.org.
Photo: Joe Pugliese

“This,” says Matthew Carpenter, “is my favorite exercise.” I peer over his shoulder at his laptop screen to see the math problem the fifth grader is pondering. It’s an inverse trigonometric function: cos^-1(1) = ?

Carpenter, a serious-faced 10-year-old wearing a gray T-shirt and an impressive black digital watch, pauses for a second, fidgets, then clicks on “0 degrees.” Presto: The computer tells him that he’s correct. The software then generates another problem, followed by another, and yet another, until he’s nailed 10 in a row in just a few minutes. All told, he’s done an insane 642 inverse trig problems. “It took a while for me to get it,” he admits sheepishly.

Carpenter, who attends Santa Rita Elementary, a public school in Los Altos, California, shouldn’t be doing work anywhere near this advanced. In fact, when I visited his class this spring—in a sun-drenched room festooned with a papercraft X-wing fighter and student paintings of trees—the kids were supposed to be learning basic fractions, decimals, and percentages. As his teacher, Kami Thordarson, explains, students don’t normally tackle inverse trig until high school, and sometimes not even then.

But last November, Thordarson began using Khan Academy in her class. Khan Academy is an educational website that, as its tagline puts it, aims to let anyone “learn almost anything—for free.” Students, or anyone interested enough to surf by, can watch some 2,400 videos in which the site’s founder, Salman Khan, chattily discusses principles of math, science, and economics (with a smattering of social science topics thrown in). The videos are decidedly lo-fi, even crude: Generally seven to 14 minutes long, they consist of a voice-over by Khan describing a mathematical concept or explaining how to solve a problem while his hand-scribbled formulas and diagrams appear onscreen. Like the Wizard of Oz, Khan never steps from behind the curtain to appear in a video himself; it’s just Khan’s voice and some scrawly equations. In addition to these videos, the website offers software that generates practice problems and rewards good performance with videogame-like badges—for answering a “streak” of questions correctly, say, or mastering a series of algebra levels. (Carpenter has acquired 52 Earth badges in math, which require hours of toil to attain and at which his classmates gaze with envy and awe.)

Initially, Thordarson thought Khan Academy would merely be a helpful supplement to her normal instruction. But it quickly become far more than that. She’s now on her way to “flipping” the way her class works. This involves replacing some of her lectures with Khan’s videos, which students can watch at home. Then, in class, they focus on working problem sets. The idea is to invert the normal rhythms of school, so that lectures are viewed on the kids’ own time and homework is done at school. It sounds weird, Thordarson admits, but this flipping makes sense when you think about it. It’s when they’re doing homework that students are really grappling with a subject and are most likely to need someone to talk to. And now Thordarson can tell just when this grappling occurs: Khan Academy provides teachers with a dashboard application that lets her see the instant a student gets stuck.

“I’m able to give specific, pinpointed help when needed,” she says.

The result is that Thordarson’s students move at their own pace. Those who are struggling get surgically targeted guidance, while advanced kids like Carpenter rocket far ahead; once they’re answering questions without making mistakes, Khan’s site automatically recommends new topics to move on to. Over half the class is now tackling subjects like algebra and geometric formulas. And even the less precocious kids are improving: Only 3 percent of her students were classified as average or lower in end-of-year tests, down from 13 percent at midyear.

For years, teachers like Thordarson have complained about the frustrations of teaching to the “middle” of the class. They stand at the whiteboard, trying to get 25 or more students to learn the same stuff at the same pace. And, of course, it never really works: Advanced kids get bored and tune out, lagging ones get lost and tune out, and pretty soon half the class isn’t paying attention. Since the rise of personal computers in the early ’80s, educators have hoped that technology could solve this problem by offering lessons tailored to each kid. Schools have blown millions, maybe billions, of dollars on sophisticated classroom technology, but the effort has been in vain.

Khan’s videos are anything but sophisticated. He recorded many of them in a closet at home, his voice sounding muffled on his $25 Logitech headset. But some of his fans believe that Khan has stumbled onto the secret to solving education’s middle-of-the-class mediocrity. Most notable among them is Bill Gates, whose foundation has invested $1.5 million in Khan’s site. “I’d been looking for something like this—it’s so important,” Gates says. Khan’s approach, he argues, shows that education can truly be customized, with each student getting individualized help when needed.

Not everyone agrees. Critics argue that Khan’s videos and software encourage uncreative, repetitive drilling—and leave kids staring at screens instead of interacting with real live teachers. Even Khan will acknowledge that he’s not an educational professional; he’s just a nerd who improvised a cool way to teach people things. And for better or worse, this means that he doesn’t have a consistent, comprehensive plan for overhauling school curricula.

Whatever Khan’s limits, his site has become extremely popular. More than 2 million users watch his videos every month, and all told they answer about 15 questions per second. Khan is clearly helping students master difficult and vital subjects. And he’s not alone: From TED talks to iTunes U to Bill Hammack the Engineer Guy, new online educational tools are bringing the ethos of Silicon Valley to education. The role these sites can (or should) play in our nation’s schools is unclear. But classes like Thordarson’s are starting to find out.

Teachers have long known that one-on-one tutoring is effective, but in 1984, the education scholar Benjamin Bloom figured out precisely how effective it is. He conducted a metastudy of research on students who’d been pulled out of class and given individual instruction. What Bloom found is that students given one-on-one attention reliably perform two standard deviations better than their peers who stay in a regular classroom. How much of an improvement is that? Enough that a student in the middle of the pack will vault into the 98th percentile. Bloom’s findings caused a stir in education, but ultimately they didn’t significantly change the basic structure of the classroom. One-on-one instruction, after all, is insanely expensive. What country can afford one teacher per student? Read More