Christina is a modern, multitasking, American 15-year-old—fiddling with her new iPod, sassing the tall boy slouched beside her, and getting an impromptu lesson in Filipino culture at an after-school program in Oakland, California. “I speak Tagalog and Filipino,” says the group’s counselor, Michelle Ferrer, “two languages from the island where my family comes from.” Christina is puzzled. “The Philippines is an island?” she asks skeptically. Ferrer nods and Christina frowns. “I thought it was in China,” she says. Ferrer tries not to laugh. “Girl, you thought I was Chinese?” she teases gently. “No,” Christina clarifies, “I thought the Philippines was a country in China.”

In California, where Christina lives, more than 1 in 4 of the state’s residents were born outside the United States. Schoolchildren speak more than 60 languages at home. Globalization is everywhere you look. Here in Oakland, an 11-year-old African-American boy has impressed international audiences with his uncanny Chinese arias. In nearby Fruitvale, nearly 100,000 locals turned out last fall for a Mexican Día de los Muertos celebration. To the south, in Silicon Valley, a Bollywood cineplex effortlessly sells out its Hindi screenings. A few blocks from my San Francisco apartment, a shop that specializes in goods from Brazil (the area around Goiania, specifically) shares its block with a Vietnamese restaurant and a yoga studio, where yuppies chant in Sanskrit as they bend and sweat; outside, Caribbean reggaeton blares from the windows of Japanese tuner coupes.

But for all the changes globalization has brought to the average American kid’s cultural and commercial ecosystem, the average classroom has lagged far behind, even in cosmopolitan California....