MIAMI (AP) ― Duna Lopez started school in Miami last fall not knowing a single word of English.

The 8-year-old girl from Barcelona, Spain, with dark blond hair was placed in the Coral Way Bilingual K-8 Center, the nation’s oldest bilingual school. For half the day, she receives classes in Spanish; it’s English for the rest. During language arts, she gets pulled out with three other new arrivals for extra help on grammar and phonics.

After seven months, she’s one of the most active participants in class.

“In five months, like that, I learned it,” she said.

Duna’s success is exceptional, but the language challenge she faced is increasingly common across the U.S. educational map. Nationwide, nonwhites are expected to become a majority of the population within a generation, and schools are at the cutting edge of that historic shift. 

School-age children who speak a language other than English at home are one of the fastest-growing populations. Their numbers doubled between 1980 and 2009, and they now make up 21 percent of school-age kids.

There were 4.7 million students classified as “English language learners” ― those who have not yet achieved proficiency in English ― in the 2009-10 school year, or about 10 percent of children enrolled, according to the most recent figures available from the U.S. Department of Education.

“This is part of a new reality that our public schools are facing,” said Robert Linquanti, an expert in English learner students for WestEd, an education research agency based in San Francisco. “It’s been coming for a long time but now it’s hitting a tipping point.”

Of all the challenges facing minority students and their schools, English learners are arguably the most disadvantaged. It’s hard to find enough teachers who are qualified to instruct them, and there’s little consistency in the programs used to educate them.

The country is divided over the best way to educate them, with bilingual programs gathering steam but also provoking a sometimes heated debate with those who favor an English-only approach. English learner students are more likely to be in poor, overcrowded schools and in many places represent an added cost to already cash-strapped school districts.

The longer these students stay in special language programs, the further they fall behind in other subjects. In several states, their graduation rates are at less than 60 percent, and as low as 29 percent in Nevada, according to federal data.

Just 7 percent of fourth-grade and 3 percent of eighth-grade English learners scored “proficient” or above in a nationwide reading exam, and thousands languish for years in ineffective English-as-a-second-language programs.

On a scale of one to 10, the education of the nation’s English learners is “below five,” said Gary Cook, a specialist with the Wisconsin Center for Education Research.

“Their success is our success,” Cook said. “If they really can’t meet the educational expectations of what’s coming ― that is, the need to be knowledge workers, not necessarily physical workers ― then we’re in a world of hurt.”

The vast majority of English learners, more than two-thirds at the elementary school level, were born in the United States. They represent many different languages and ethnicities, but the majority is Hispanic. Overall, 38 percent of Hispanic fourth-grade students were identified as English learners, as well as 20 percent of Hispanic eighth-grade students, according to the 2011 National Assessment of Education Progress math test.

Latino students overall have some of the highest dropout rates and the lowest share of the population with a bachelor’s degree. The language barrier does not affect the majority, but for those who enter school as English learners the challenges are even greater.

Asian students represent the second largest group of English learners.

States such as California, Texas, New Mexico and Nevada have some of the largest proportions of English learners in their school-age populations. They also are widely concentrated in low-income, urban schools. A study by the Urban Institute found that 70 percent are educated in 5,000 elementary schools, just 10 percent of the nation’s schools.

The segregation of these students is reflective of both neighborhood segregation and a decision on the part of some districts to group these students together in order to provide them with qualified teachers and bilingual programs that are scarce, said Richard Fry, a senior research associate for the Pew Hispanic Center. But the schools they attend also tend to have the highest rates of poverty, larger pupil-teacher ratios and bigger schools.

“They are clearly at risk,” Fry said.

How best to teach English learners is under debate.

The research is inconclusive, though there has been recent momentum for bilingual education programs such as the one at Coral Way, which has been at it longer than most schools. The school adopted a bilingual program for all students, regardless of language proficiency, in the 1960s after receiving a wave of Cuban immigrants fleeing the 1959 communist revolution.

Believing they’d eventually return to Cuba, many families wanted to make sure their children didn’t lose their Spanish. Most never returned to the island, but the dual-language program remained and the school has consistently been given an “A’’ by the state.

Virginia Collier and Wayne Thomas from George Mason University in Virginia studied more than 6 million student records and found that full-immersion bilingual programs in which native and nonnative students are given instruction in both languages are the most effective. They studied bilingual programs in the Houston Independent School District and found that native-Spanish speakers were at or above grade level in English and Spanish in first grade through fifth grade.