Thirteen students who would have attended Marumsco Hills Elementary School this year chose to transfer instead as part of No Child Left Behind requirements.

The Woodbridge school was required to offer transfers to its students after its poor performance on one part of the state Standards of Learning tests. The requirement is part of new federal school performance guidelines.

Most of those who transferred were kindergartners, Marumsco Hills Principal Joanne Alvey said. Three children are now attending Swans Creek Elementary, and 10 are attending Mary Williams Elementary, which opened this year.

"I was saddened to see anybody leave," Alvey said. "But I was hoping there would be under 20" transfer students.

Nationwide, the federal government now judges schools by results on state standardized math and English tests among several groups of students. In Prince William and elsewhere in Northern Virginia, the groups are whites, blacks, Hispanics, students from poor families, students with disabilities and students with limited English skills.

If students in one group perform poorly, the entire school can fail to make "adequate yearly progress" under the federal law. The rationale is that schools will no longer be able to disguise the poor performance of certain groups by averaging their test scores with those of their higher-performing classmates.

The law places penalties on so-called Title I schools -- those that receive federal money because they have a high number of students from poor families. Title I schools must offer students the option of transferring until their home schools make adequate progress two years in a row. More affluent schools that do not make enough progress must create a schoolwide plan to bolster scores.

Marumsco Hills, a Title I school fully accredited by the state, failed to make adequate progress among third-graders with limited English skills. Two other county Title I schools, Dale City and River Oaks elementary schools, are checking their test scores with the state; their status is not determined, so they did not have to offer transfers.

No Manassas or Manassas Park schools had to offer transfers.

If test scores at Marumsco Hills rise two years in a row, the students who transferred will be allowed to remain at Swans Creek and Williams but will have to provide their own transportation, said Joyce Mannherz, Title I supervisor for the school systems.

This year, the school system pays for transfer students' transportation. The cost for the 13 Marumsco Hills children has not been determined, but it is likely to be close to $2,500 per student, the amount it costs annually to transport students to the county's many specialty programs, according to Ed Bishop, the county's director of transportation.

In comparison, it annually costs about $352 per student to transport them to their neighborhood schools. The money to pay for the transfer program comes out of Title I funds for the county, but no programs have been cut to pay for the busing, Mannherz said.

Alvey said she only heard from one parent regarding the transfer, and that parent ultimately decided to keep her children in the school.

Alvey said she was not surprised that most parents who are familiar with the school chose not to move their children.

The school has several programs designed for its large population of Spanish-speaking children, including small class sizes and a teacher trained to teach English as a second language in every classroom.

This year, teachers will be trained in "sheltered instruction," a method of mixing vocabulary lessons with other subjects, such as math or science.

"It's very powerful if you do it right," she said.