A crucial question facing a growing number of schools in the Washington area is how the education of American-born students is affected where they are a minority among foreign students.

An expression of that concern is an Arlington school task force assessing the merits of limiting the number of non-English-speaking students at any given school. The undertaking was prompted, in part, by some parents of American-born pupils at Key Elementary School, where 70 percent of the students are foreign, most of them Hispanic.

Burtis M. Dougherty, president of the civic association in Lyon Village, a relatively affluent subdivision within Key's boundaries and a member of the study group, said some parents there have enrolled their children in Arlington's two predominantly white alternative schools or in private schools to avoid sending them to Key.

"I think, frankly, that some people have expressed concern because they don't like that many nonnatives around," Dougherty said. "Others have expressed it for legitimate educational reasons."

Although no educators interviewed could cite a study showing that there is a negative impact on American-born students from a large foreign student population, some said they believed that foreign students may slow the pace of instruction, especially if they do not receive adequate instruction in English as a Second Language and are put into the mainstream too quickly.

"The impact is in the eyes of the beholder," said John L. Crowder, the Arlington school official leading the task force. "Some parents maintain that the teacher's time is being split between the American students and {the non-English-speaking} students, and some of them think that's not fair."

Arlington County Board member Dorothy H. Stambaugh said that what bothers parents most is that traditional American supplements to a child's learning experience, such as scout groups, will be hard to keep alive at schools with large foreign populations because immigrant parents feel less attachment to these activities.

"It's not whether it's good or bad," said Stambaugh of the large number of Hispanics at Key, "but that it deviates from the norm . . . that bears review."

Dedication motivates educators to reach out to immigrant parents and to design programs tailored to foreign students' needs. But so does fear that if they do otherwise, educational standards for everyone will suffer.

"We're very proud of our educational system, and we know these children can have a negative impact on the other children if we don't provide these services," said Ester Eisenhower, who coordinates the foreign student programs in Fairfax County. "It's not philanthropy. We're not martyrs and saints . . . . It's good business."