On a sunny January morning in East Denver, Brian Weber, head of the Denver Language School (DLS), greets parents by first name as they pull up to the curb. He chitchats for a few moments while the kids head to the playground to romp around before classes start. The scene seems normal enough for an American elementary school. That is, until a foreign twang catches your ear, and you realize the first-graders clambering around the jungle gym—all of them Caucasian—are talking to each other in Mandarin Chinese.

At DLS, a public charter school with 450 students ranging from kindergarten to fourth grade, these conversations happen every day. The school’s language immersion curriculum is arguably the fastest-growing foreign-language education model in America—and as it turns out, an elaborate study in what some might call peaceful imperialism. As its name implies, language immersion students don’t just learn a foreign language; they learn every subject in a foreign language, starting as young as preschool. Bilingualism has been shown to enhance brain development in young kids, helping them become more creative, better problem-solvers, and more adept at multitasking. These qualities, along with the exposure language immersion gives kids to other cultures, have made it madly popular with parents: DLS received 500 applications for 250 spots when it opened in 2010. “I think it’s the most awesome thing in the world,” says Lori Pace, parent of a DLS third-grader. “It’s a unique and rewarding opportunity, and the fact that DLS is a public charter school is an added benefit.”

Language immersion schools have also created a situation in which foreign governments partially subsidize America’s public education system—and probably the only scenario wherein entities such as the National Security Agency and the Department of Defense donate millions of dollars to elementary schools. According to Weber and other proponents, language immersion produces smarter kids with broader worldviews. However, given the still-evolving performance of these students on English-language standardized tests, it also makes some wonder if American kids should really be spending all day learning the three Rs in a foreign tongue.

Language immersion was initiated in 1965 by English-speaking Canadian parents who wanted their kids to learn French. Inspired by Canada’s success, UCLA professor Russell Campbell launched America’s first immersion program in Culver City, California, in 1971; the model has recently exploded in popularity thanks to the National Security Language Initiative, which was launched by President George W. Bush in 2006 to expand America’s pool of future translators and diplomats. You’ll find these schools scattered from Oregon to Washington, D.C., and the model is spreading fast in unlikely places. For instance, by 2013, Utah will have 78 dual-immersion schools (which split teaching between English and a foreign language), with a goal of increasing that number to 100 by 2014.

There are four full immersion schools in Colorado that teach every core subject in the target language. All are located on the Front Range: DLS (East Denver) and Aurora’s Global Village Academy (GVA) are public, while Denver Montclair International School (DMIS) in Lowry and University Hills’ Colorado International School are private. Among the four schools, kids can learn in German, French, Spanish, Farsi, or Chinese.

When Weber and two Stapleton moms founded DLS, then a K­–2 school, in 2010, it became the first and only Denver public school to offer full immersion. Weber, a former Rocky Mountain News education reporter and vice president of the Stapleton Foundation, which contributed $300,000 to the launch of DLS, never intended to run the school. He’s fluent in neither of the school’s two languages, Chinese and Spanish; he simply believes in the model. “Immersion challenges your brain more—makes it work harder,” says Weber, who stepped away from day-to-day operations in March to focus on strategic development.

Strolling through the halls, he laments the way demand for language immersion in Colorado is overwhelming supply. The average class size at DLS is large—27 kids—but a teaching assistant in every room helps keep things manageable. Inside one DLS kindergarten classroom, the language immersion methods are on display. A girl gets frustrated and starts rambling in English only to be answered in Spanish by her teacher, who gestures with her hands to help convey what she’s saying. Next door in a first-grade Mandarin room, students work on pronunciation in Pinyin, an English alphabet liaison language, by smacking the Chinese words’ English equivalents on the wall with a fly swatter. The Chinese alphabet has between 2,000 and 5,000 characters, and Weber says a couple of his third-graders are getting close to knowing them all. Surely they must be native speakers? “No,” he says. “We’ve got little blond-haired, blue-eyed white girls who win Chinese speaking contests.”

Its popularity notwithstanding, language immersion’s merits are often better understood over time. One of the problems with using this model in public schools, particularly in the early years, is that students still must take English-language standardized tests—and be measured against peers who are specifically taught to succeed on those tests. GVA students, for example, have achieved modest CSAP results since the school’s 2007 founding. (DLS third-graders took their first CSAPs this past spring.) “Some people worry about the idea of no English for a few years,” says Amy Anderson, associate commissioner of innovation, choice, and engagement at the Colorado Department of Education. “People will start paying more attention if CSAP scores back it up.”

Myriam Met, former director of the National Foreign Language Center at the University of Maryland, and one of the country’s leading experts on immersion, acknowledges the numbers can present a mixed picture. “Evidence has shown that full immersion students’ test scores do tend to lag behind their peers’ until English language and literacy are introduced,” she says. “But then they tend to catch up and, in many cases, pull ahead.” Indeed, a 2007 study from the Connecticut Department of Education found that students who had received long-term instruction in foreign languages scored considerably higher on both the verbal and math portions of the Scholastic Aptitude Test (SAT), and other studies have correlated bilingual proficiency with higher scores on a variety of standardized aptitude tests.

Proponents of language immersion don’t need test scores to validate the programs’ success. DLS fielded more than three applicants for every open desk this spring and was the most sought-after kindergarten program in the 2012-13 Denver Public Schools choice lottery process. It has drawn more than 70 students from private schools, an unheard-of number for a public institution. Laura Montoya, a mother of three DLS students, says she and her husband, who’s from Colombia, felt like they were giving their children “a gift” by enrolling them in an immersion school. “I think it opens their eyes culturally as wide as they can be opened. They’re color-blind,” she says. “DLS is truly a little United Nations in the middle of Denver, which is otherwise pretty homogenous.”

DLS also adds a layer of diversity with its instructors. The school employs five Chinese teaching assistants, two of who were college professors before coming to Denver. DLS pays a portion of their salaries; the rest, including a $3,000 monthly living stipend, is covered by an arm of the Chinese government whose goal is to spread the Chinese language to foreign lands—including, as it happens, to its prime competitor among global superpowers. France’s government also gives about $230,000 in tuition assistance to DMIS (and evaluates it annually since the school follows a French curriculum), and Spain’s Ministry of Education subsidizes GVA. Naturally, the U.S. government also chips in. DLS and GVA recently received $1.4 million multiyear grants from the Department of Education’s Foreign Language Assistance Program, which gets some of its funds from the Department of Defense.

As he continues the tour of DLS, Weber says he knows this collision of American and foreign cultures is a delicate subject. “We’ve had a couple of people ask us if we educate students on Mao; do they have The Little Red Book; are we indoctrinating them into communism?” he says. (They don’t, and they aren’t.) And yet, DLS is a place where kids learn Martin Luther King Jr.’s I Have a Dream speech in Spanish, hear about the Pilgrims in Mandarin Chinese, and stage a lavish show to celebrate the Chinese New Year.

To Weber, concerns about imperialism are understandable but misplaced. He cites the experience of a DLS first-grade Chinese teaching assistant named Luo Yun as a more meaningful example of the school’s reach and results. Luo is 36 and in his first of two years at DLS. He taught English literature for 12 years at a university in China before being chosen by the Chinese education ministry, on his second try, to teach in Denver. So far, he’s been surprised and impressed by what he’s seen from his students, and he offers compelling testimony about the effects language immersion can have. “I’m actually a little amazed by the progress the kids have made,” Luo says. “They use what they’ve learned to express themselves in daily life almost immediately.”