Nine-year-old Mariela Jimenez scrutinized the wooden grain of her desktop, as if in search of the words she would enter in her journal.

After reflection, she penciled a paragraph of Spanish into a spiral notebook. The subject was snow.

"I'm looking forward to winter," she wrote in a steady cursive hand, "because I want to play in the snow with my friends, and build a huge snowman and put a carrot nose on him, and have fun running in the snow, and also going to school and getting a lot of homework and learning a lot."

A recent arrival in Arlington, the Bolivian fifth-grader at Barcroft Elementary School is typical of a growing number of Washington area schoolchildren for whom English is a foreign language. As they have for most of the last decade, local school districts reported record numbers of such children in their classrooms this September.

While non-English-speaking children make up about 6 percent of the nation's public school enrollment, many local districts, particularly those inside the Capital Beltway, have twice that proportion. Arlington has the highest in the Washington area -- 16 percent.

As the number of immigrant children in area schools has grown, so has the debate about the best way to educate them. Of particular concern are students who, like Mariela, come from Central and South America. Not only do they form the bulk of this area's immigrant influx, they lag as a group, along with black youngsters, behind Asians and whites in academic performance.

Educators say the challenge is teaching those children enough English to adapt to life in this country while providing sufficient academic coursework to keep them abreast of their peers.

Most recently, Montgomery County's program for immigrant students was criticized by a consultant on minority achievement for focusing too much on language acquisition and not providing enough for students' non-English-speaking parents.

Most of Mariela's first day at Barcroft -- delayed a week while her mother arranged necessary immunizations -- was spent in Elizabeth Iacoponi's classroom with fully fluent children. There, Mariela, who looks more like a second-grader than a fifth-grader, studies math, physical education and art, subjects in which English is not crucial.

Three hours a day, however, Mariela is in a trailer behind the school building, where she and 15 students from Ethiopia, China, Vietnam and Latin America learn the fundamentals of English. Her first day's activity was making a bingo board using parts of the body to learn words such as hand, eye, head, foot and mouth."

She also wrote in her journal, the basis of a daily dialogue with the language teacher, and a way for Mariela to practice writing English. Her teachers say Mariela has now begun interspersing a few words of English into her Spanish journal entries.

Mariela herself told a recent visitor to her classroom that she is trying not to feel too discouraged.

"I can't understand a lot of things," she said after two weeks in class. "The teacher talks so fast. But I get a little better all the time."

Mariela, who was born in the Bolivian city of Cochabamba, speaks less English than any of her classmates. Yet her teachers say she has a better than average chance to succeed. While many recent arrivals in area school systems are illiterate in their native languages and have fled war and poverty in their former countries, Mariela has educated parents, a good academic foundation and a desire to learn.

For Mariela, the process of learning English will be a gradual weaning from Spanish. On her first visit to the school library in mid-September, she eagerly snatched up three Beatrix Potter storybooks from the modest Spanish language section. Kelly Miller, the director of the Barcroft school's language program, told her she would have to select at least one book in English on subsequent visits.

The prescription of daily three-hour language classes for Mariela came after a daylong visit in late August to the Arlington school system's Intake Center, which operates as a kind of academic Ellis Island. There, foreign-born children are interviewed, tested for their level of literacy and placed in county schools. So far this school year, the Intake Center, at Key School, has seen 700 new students, a record number.

Ofelia Cid, who tests most of the students coming into the center, gave Mariela simple commands in English that day in late August.

"Touch your finger to your nose, Mariela," or "Can you show me which of these things in the picture don't belong with the others?"

To most of them, Mariela, whose command of English was then limited to a few simple greetings such as "Hello," responded with silence.

Increasingly, Arlington is employing a strategy of placing immigrant children, even those who are behind academically, in a class with children of the same age.

"It would be too demoralizing for them to be in class with much younger students," said Emma Hainer, coordinator of English for Speakers of Other Languages programs for Arlington.

"Wherever she was taught, they seem to have done a good job," Iacoponi said, recalling the time she gave the children a blank map to fill in the names of the continents, and Mariela, unlike most of her American classmates, "got them all right."

Mariela spent what her mother described as two less-than-ideal months in a Los Angeles school after she, her parents and sister moved there from Bolivia in March. Her father, an architect in Bolivia, now cleans offices and lays floor tiles in Los Angeles. Her sister has just begun her senior year in high school there.

"I thought {Mariela} was picking up bad habits from the other kids" in Los Angeles, said Gloria Jimenez, her mother, who taught grade school in Bolivia, but said she will have to settle for a lesser job here. "There seemed to be a lack of morals, a lack of respect for adults, for teachers and for each other."

So Gloria Jimenez decided that Arlington, where her brother lives, would offer more to Mariela. The two moved here last summer. Jiminez said she hopes her husband, daughter and another son, who is still in Bolivia, will eventually join them in Arlington.

"Things are working out much better here," Jimenez said.

Concerns about how best to teach children such as Mariela has led Arlington to alter its programs for non-English-speaking children over the years, according to school officials.

"We found over time that our kids need more than language and grammar," Hainer said. "We are no longer watering down our curriculum. That way, these kids don't fall behind while they are with us."

Children graduate from Arlington's language program on the recommendation of their classroom teachers and when they can demonstrate reading skills within two grade levels of their current grade. In many cases, they still meet with language instructors to refine their English skills even after they have entered the regular classroom full time.