NASHVILLE, Tenn. -- Plaintiffs challenging the rezoning of Nashville's public schools claim the plan is a pretext for resegregation.

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Three families who filed suit against Metro Schools are asking a judge to give the case class-action status. Giving the case a class-action status would open it up to thousands of Nashville families.

The NAACP filed the lawsuit on behalf of the three families and calls for the elimination of the zoning plan that took effect this year. The group claims the plan is racist because it concentrates African-American students into a few schools.

The school system claims the plan was never based on race.

"I feel the whole purpose and goal is to get the majority of the black students out of the Hillwood cluster," said former Metro School Board member George Thompson.

On the witness stand Tuesday, Frances Spurlock said her daughter, who is African-American, was offered a choice of two failing schools. The 6th grader had previously attended a majority white school with a much better academic record.

"Why only offer us schools that are not up to par?" she asked.

A U.S. District judge has already ordered that the Spurlocks' daughter be allowed to return temporarily to her previous school after he learned her new school had not received textbooks three weeks into the school year. District Judge John Nixon is considering an injunction in the case, which is expected to last several days.

Assistant Metro Attorney Kevin Klein told the court in opening statements the school district had been trying to deal with the problem of school utilization for years.

"The buildings were not being used in the most efficient manner," he said. "Some were only used at only 50 percent of their capacity while some had too many people."

In 2007, with the system facing a possible state takeover for poor academic progress, the school board appointed a task force to explore rezoning options. The board eventually adopted that panel's recommendation on a 5-4 vote, with all black members but one voting against and all white members voting in favor.

"The impact has not been discriminatory," Klein said. "There have not been sweeping changes in demographics" at the affected schools.

A second plaintiff, Carol Lewis, told the court she opted to send her African-American granddaughter, of whom she has legal custody, to John Early Middle School under the mistaken belief that it was a magnet school.

It had been a magnet school the previous year and some papers she was sent from the school district even referred to it as a magnet school.

But when she took the child to school on the first day she realized her mistake and tried to transfer to a majority white school with a better academic record. That transfer was denied.

The Spurlocks also had tried to transfer their daughter out of John Early with no success. Frances Spurlock said in court that white families she knew had been able to transfer their children.

If the families win the suit, class-action status would allow others to benefit without actually signing on to the suit itself.

Reporters Regina Raccuglia and Jonathan Martin contributed to this story.