As a third wave of coronavirus infections has begun to take off across much of the country, San Francisco has been a bright spot. After experiencing a surge of cases over the summer, the city has tamped down infections to near their lowest levels since the pandemic began. Restaurants, movie theaters, and museums are open at 25 percent of capacity.

One crucial part of the city, however, remains firmly closed: The public schools.

Even as private and parochial schools have begun to reopen their doors, the school district has not set a timeline for resuming in-person instruction, except to say that it is not likely in this calendar year.

The district’s decision to stay closed this fall, even as other urban districts — including New York City, Miami, Washington D.C., and Philadelphia — have opened or set dates for partially reopening, has angered many parents, local health experts and the mayor, London Breed, who does not control the school system.