Raleigh, N.C. — Thousands of Wake County elementary school students will change schools this year. The school board voted Tuesday night in favor of a controversial reassignment plan despite an outcry from parents.

"I expect that each of you, unbiased, have the best interest of all the children in the district,” parent Tom Luzzi said.

Reassignment is necessary to balance diversity and keep some schools from falling behind, Wake County Schools Superintendent Del Burns has said.

Administrators said they are trying to ensure "healthy schools" in which fewer than 40 percent of students are from low-income families. Officials determine a school's poverty rate based on the percentage of students qualified to receive free or reduced-price lunches.

“Whole groups of children have to be moved, just to get to that small handful of children needed,” parent Jennifer Etkin said in criticizing the reassignment plan.

Some parents told the school board Tuesday night that moving 6,464 students partially for diversity is not fair and that the school district is losing trust.

"Its reassignment decisions are for the children of poverty, and if we question it, it says we are elitist, classist or racist,” parent Jody Barish said.

Parents against reassignment want the school district to prove that balancing economic mixes produces more successful schools. Administrators argue that a study to prove that is impossible.

"To do that in a scientific lab kind of way, we'd have to be willing to sacrifice one group of youngsters to see what the effect was,” said David Holdzkom, Wake County assistant superintendent for evaluation and research.

Administrators also judge a school's diversity on its end-of-grade exam scores and the number of students in special education or with limited proficiency in English.

About 20 percent of the students changing schools this fall are being moved to balance diversity. Students are also being reassigned to ease crowding at existing schools and to fill seats at three new schools – Laurel Park, Mills Park and Sycamore Creek.

Supporters argue that reassignment is a must for a system growing as fast as Wake County. It became the largest in the state in 2007 and expects to grow by 6,000 to approximately 140,000 students next year.

The school board agreed to extend a grandfather option for rising fourth- and fifth-graders for both existing and new schools.

The school board also talked about year-round versus traditional-calendar schools. School board member Ron Margiotta wanted to convert two of the new elementary schools from year-round back to a traditional calendar. The school board voted against that.