Students in the nation’s capital should not return to full, in-person learning until there is a reliable vaccine or cure for the novel coronavirus, according to recommendations released Thursday by a group of advisers appointed by D.C. Mayor Muriel E. Bowser.

The report by Bowser’s ReOpen DC Advisory Group divides the city’s reopening into four phases, with the fourth phase triggered when there is a vaccine or cure. It recommends that before that, students should return to campuses on modified schedules, switching between in-person and distance learning depending on the day. Even if schools can accommodate them, families should not be required to send their children to school buildings — and will have the option of distance learning — if they feel unsafe.

The mayor’s administration has said that these recommendations would influence how she reopens the city, but she is not bound to adopt them. She is expected to announce more concrete education plans for summer and the beginning of the next academic year at a news conference Friday.

But with the city still not yet in Phase 1 of her reopening plan — Bowser (D) said that may happen as early as next Friday — the report largely underscores that city leaders, here and across much of the country, still don’t know exactly what school will look like in the fall.

Under the recommendations, some students would be allowed to return to campuses in Phases 2 and 3 of the reopening plan, which would occur when there is only localized virus transmission and officials can track how each patient became infected.

When schools partially reopen in Phase 2, schools should operate below their building’s capacity to allow for proper social distancing, with students attending school on some days and participating in distance learning on others. The report recommends that schools across the city operate with similar schedules. No more than 10 people, including teachers, should be in each classroom. The city should release guidance for families in case they want share child-care responsibilities with classmates or neighbors.

Lunch and breakfast should be eaten in classrooms instead of cafeterias. In older grades, teachers, not students, should switch classrooms at the end of the period. Students should also have staggered arrival and dismissal times, instead of all rushing into school at one time, the report recommends.

At a news conference Thursday, Bowser unveiled recommendations for opening several parts of city life made by the ReOpen DC Advisory group, which is chaired by former national security adviser Susan E. Rice and former homeland security secretary Michael Chertoff.

“It is not an off-and-on switch,” Bowser said. “We will not be able to go back to life as we enjoyed in February, but we are incrementally adding activities back into our lives.”

Details emerging in the District and around the country are beginning to hint at how schools could operate in the coming months. The Centers for Disease Control and Prevention released its road map to reopening schools this week and, similar to the recommendations in the District, advised that schools in low-infection areas could reopen with certain precautions, including desks spaced at least six feet apart and facing the same direction and an ample supply of masks and hand sanitizer.

Earlier this week, at a virtual leadership conference, top D.C. Public Schools officials provided school leaders a glimpse of what its more than 110 campuses could look like in the fall — though the ideas presented there also aren’t known to have the mayor’s backing.

One potential scenario included having students attend school one or two days a week and participating in remote learning on the others, according to school leaders familiar with the presentation who were not authorized to speak about it. Another included attending school one week out of every three weeks.

Richard Jackson is a former D.C. high school principal who heads the Council of School Officers, a union for mid-level leadership in the school system. He said he has been fielding feedback from principals and that it is still unclear if these scenarios are feasible to implement in schools. He has called on the school system to include principals’ input on how schools should operate during the health emergency.

“We are having to react to ideas instead of being at the table able to make ideas,” he said. “We are in the early stages.”

Council member David Grosso (I-At Large), who co-chairs the education committee, said the suggestions could work but would require flexibility from parents and employers across the region.

“It’s going to depend on the business community understanding all of this,” Grosso said. “Employers will need to be flexible. . . . I think everyone will step up to the plate.”

The ReOpen DC report also included recommendations on how to reopen early-childhood care centers and universities. Some day cares would reopen in Phases 1 and 2, and all licensed facilities would be able to open in Phase 3, which is triggered when there is sporadic transmission. When all of the licensed facilities are reopen, the report recommends that they be limited to 10 people, including adults, in each room.

The report recommends that in Phase 1, the limited number of day cares open should be for children of parents who need to return to work, and that they conduct regular temperature screenings.

It advised that youth sports be canceled until there is further public health guidance on the matter. Field trips should also be canceled. The city should adopt a policy that requires students and staff members to remain home if someone in their household has a pending coronavirus test, according to the report.