Parents in Loudoun County face a choice for the fall: They can either send their students to bricks-and-mortar school for a portion of every week, or they can keep their children at home for full-time distance learning as the school district responds to the upheaval caused by the novel coronavirus pandemic.

The Loudoun County School Board voted by a slim margin to endorse the two-track plan at a contentious, marathon virtual meeting Monday that began at 4 p.m. and lasted past midnight. The strategy marks a significant update to a tentative set of guidelines, released by the superintendent in mid-June, that envisioned all students attending school in person for two days each week and did not give the option of 100 percent virtual school.

Parents and teachers must indicate their preference by July 13. The timeline is meant to give administrators sufficient time to assign staff members to either face-to-face or virtual roles, and to develop the complex schedules required for staggered bricks-and-mortar schooling.

“We do not have all the information that we would like to have about the situation that we are in,” Schools Superintendent Eric Williams said before the vote. “Still, there are decisions that must be made.”

Under the plan endorsed Monday, the amount of in-person schooling the Northern Virginia district of 84,000 offers will differ depending on which phase of Gov. Ralph Northam’s reopening process the state has entered by the time school starts. Although now in Phase 2, Virginia is slated to transition to Phase 3 on Wednesday, meaning child-care centers will reopen and the cap on social gatherings will rise to 250.

If the state is still in Phase 3 by the time school begins, families who select the hybrid option will send their children to school two days each week, with students learning at home for the remaining three. If the state has reverted to Phase 2, all students will be required to learn 100 percent virtually except for students with disabilities, English-language learners and students in prekindergarten through third grade.

If the state has fallen back to Phase 1, pretty much everyone will be forced to learn from a distance. Only students with disabilities will be permitted to attend bricks-and-mortar school in that scenario.

Regardless of the phase, families that select the 100 percent distance option will keep their children home. Those students will receive a combination of synchronous (real-time) and asynchronous instruction, according to documents presented to the county School Board.

Parents and staffers must abide by their choice for at least the first full semester of school. Teachers will not be guaranteed the choice they select, according to documents presented at the board meeting. Priority will be given to certain subsets of educators, including those who are subject to the Americans With Disabilities Act.

Parents who pick the hybrid learning model are promising that their children will wear face coverings on the bus and at school whenever physical distancing is impossible, according to a presentation given at the meeting. Loudoun staff members will also be required to wear masks when six feet of distance is impossible. The school system said it has purchased 71,000 cloth face coverings to provide five each to all its full-time and part-time employees.

Officials also outlined several other precautions that staffers and students must follow during in-person school: In classrooms, students will sit in desks placed in the center of 4-foot-wide circles. On the bus, students will sit one per row in every other row. And staff members and students must agree to random, no-contact temperature checks. Educators may also be asked to conduct regular temperature checks at home.

Board members voted to approve the plan 5 to 3, with one abstention, after a lengthy presentation on how socially distant school would work and an equally lengthy, sometimes tense period of questions, several failed amendments, motions, countermotions and debate.

Two members of the School Board, John Beatty (Catoctin) and Jeff Morse (Dulles), sought to seriously alter the plan in a last-ditch effort close to 1 a.m. Beatty, backed by Morse, introduced a motion that would have killed the hybrid option and instead asked parents to choose between 100 percent distance learning or 100 percent in-person learning. This idea had been touted in recent days by some parents on social media.

But the superintendent broke in to argue against the proposal. He said two days per week of face-to-face instruction represents the only way that the school system can fit students into classrooms in a socially distant, safe manner, according to his team’s projections. Beatty’s motion failed 5 to 3, with one person abstaining.

Earlier, the board sat through more than four hours of fierce, fractious public comment. Two hundred and ninety-four people signed up to speak, with each receiving 60 seconds to convey their concerns via videoconference. Parents and teachers argued with passion for both 100 percent in-person instruction and 100 percent distance learning — although many parents seemed to favor the former and educators the latter.

“We do not close our schools down for the flu,” said Loudoun parent Amanda Jorgenson, who argued that the school district should offer full-time face-to-face education. “Are you willing to say that our children may never go to school ever again?”

Parent Angela Lierni said her students’ experiences with virtual classes left them unhappy, pessimistic about the future and no longer excited about learning new things. She, too, argued for 100 percent in-person school, calling the proposed schedule of two days at school and three at home a “token” gesture.

“Students don’t learn just sitting in front of a computer,” she said. “They learn by interacting with one another.”

Teachers likewise lamented the inadequacy of virtual education and said they longed to return to the classroom. But they also said it is unfair to ask them to risk their lives, and their families’ lives, by setting foot inside the classroom every day.

“It is guaranteed that I will be within six feet of my students for 10 minutes most of every day,” said teacher Leslie McFadden. “I just don’t think we have enough answers or solutions to go back to any form of in-person learning yet, and that breaks my heart.”

Another teacher, Brandon Kalbaugh, said he would be unable to justify returning to work to his family.

“I can’t look my kids in the face,” he said, “and tell them I care more about teaching other people’s kids than being around for their future.”

Teachers will return to work — either remotely or in-person — on Aug. 19, and will spend the next few weeks preparing and training for their new reality until class begins on Sept. 8, according to the plan adopted Monday night. Loudoun’s plan closely resembles a strategy adopted by nearby Fairfax County Public Schools, which is allowing its 189,000 students to choose between entirely virtual education and at least two full days of instruction every week.

The live viewership of the virtual board meeting on Monday never dropped far below 1,000, even though the board did not adjourn until after 1 a.m.

“I don’t envy you guys,” parent Ayala Sherbow told the board, “the decision you have to make tonight.”