“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...
Hat tip to Dominic
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