In a reversal, Alexandria City Public Schools will adopt three feet of distancing in classrooms through the end of the academic year after the school board voted in dramatic fashion to repeal the superintendent’s decision earlier this week in favor of six feet.

After the vote Thursday night, which was unanimous, Schools Superintendent Gregory Hutchings Jr. must immediately work on reducing the distance between students’ desks to three feet, in accordance with guidance from the federal Centers for Disease Control and Prevention. Asked by a board member how soon that shrinking could happen, Hutchings declined to give a firm timeline but said he would form a team within days to start planning the switch.

“It would be unfair for me to throw out a date today,” he said. “I just want to make sure . . . we can work with everyone, so it’s not a complete turnover overnight.”

On Wednesday, the superintendent sent a message to families announcing that his Northern Virginia school system of 16,000 students would not immediately switch from six feet to three feet of distancing in classrooms. This went against CDC advice: The agency announced in late March that it was changing its recommendation for appropriate classroom distancing from six to three feet.

The superintendent’s decision also went against a trend in Northern Virginia in which the other major school systems had said they would adopt three feet of spacing between students receiving in-person instruction.

Hutchings’s message outraged some parents, who said they could not understand why Alexandria was apparently ignoring best practices sanctioned by the federal government’s top scientific experts.

And on Thursday, the majority of the school board spoke up to agree with them. Member Christopher A. Suarez (District A) said he was “blindsided” by the superintendent’s decision to stick with six feet, calling it “very concerning.”

“If the CDC is saying we need to get to three feet in our classrooms,” said Vice Chair Veronica Nolan (District B), “then we need to get there.”

And member Ramee A. Gentry (District C) said that since schools closed their classrooms more than a year ago, Hutchings promised that he would be guided above all else by CDC recommendations. She added: “In my five years on the school board, this is probably the most frustrated I have ever been.”

Regardless of when Alexandria accomplishes the switch to three feet, the superintendent promised that he would send roughly 3,000 children into school buildings within the next few weeks. Alexandria has to date returned approximately 5,000 children, about one-third of its student body, for two days a week of in-person learning.

In deciding which additional students to bring back to classrooms, Hutchings and his staff said, Alexandria will prioritize children who are struggling most.

First on the list are students with disabilities, those who do not speak English as a first language and those experiencing homelessness. Next up are students who are suffering emotionally, mentally or socially, followed by students who have earned D’s or F’s. Then come children who are not able to access the necessary technology for online learning and, after them, students who are learning virtually but would like to switch into the in-person program. Last on the list are new students who enrolled in Alexandria schools in January.

Using this system, Alexandria plans to send qualifying prekindergarteners through fifth-graders back into classrooms starting April 20. The following week, qualifying students in grades six through 12 will return.

The school system is working to make space for the newcomers in part by getting in touch with children who signed up for in-person learning but have so far failed to show up. School staffers are calling parents to ask why their children have remained absent and whether those families still want their children to participate in face-to-face instruction.

After these efforts, students who have not shown up for in-person learning by April 23 will be “converted back to virtual,” Hutchings and his staffers told the board.

“I want to make it very clear that we want our students back,” Hutchings said. “It is important for us to follow the CDC guidelines. . . . What we want to be able to work through is making sure that . . . we are doing all of the appropriate safety and health mitigations.”

Hutchings delivered this speech shortly before the board’s vote mandating that he switch to three feet of distance. It was the closest he came to publicly addressing the controversy over his decision to stick with six feet.

Otherwise, he said several times in the meeting — also before the vote — that he was committed to following CDC guidance and to ensuring that Alexandria’s children would learn five days a week in-person this fall. He also noted that it took “a lot of work” to transition the 5,000 students to face-to-face instruction over the past month or so. He said the school district had to be “very methodical and strategic with our planning.”

In justifying the original decision to retain six feet of distancing in classrooms, Alexandria officials published an online FAQ listing “operational considerations.” These included the fact that the CDC still defines “close contact” as being within six feet of a coronavirus case for more than 15 minutes. If the spacing between students shrank to three feet, the FAQ writers argued, Alexandria would see a spike in quarantining and a disruption in learning.

And during Thursday’s meeting, ahead of the vote, staffers from the school system and the Alexandria Health Department walked the school board through every contingency and detail of the CDC’s revised three-foot guidance. Presenters noted that the CDC says middle and high school students have to revert to six feet of distancing if community transmission of the virus is “high”; that teachers and students are still required to stay six feet apart; and that students are supposed to keep six feet from each other when they have to remove their masks for eating, singing or exercise.

The school board was not dissuaded.

“Certainly I appreciate walking through the caveats of this new guidance,” said board member Michelle Rief (District A). “That said, I think these are challenges we can tackle.”

And Gentry said she understands that the adoption of three feet could lead to more “quarantine situations.”

But “I’m quite sure the CDC was aware of that,” she said, “and still made the decision to change to three feet.”