Twenty percent of U.S. teachers say they are not likely to return to their classrooms this fall if schools reopen — and most parents and educators believe that school buildings will open, according to polls published Tuesday.

The polls — one taken of K-12 teachers and the other of parents with school-age children — found that 73 percent of parents and 64 percent of teachers said they believe that children will eventually make up for learning lost because of the disruption of school during the coronavirus crisis. And 63 percent of parents and 65 percent of teachers said they believe school buildings in their areas will reopen this fall.

The findings came in USA Today-Ipsos polls published Tuesday in USA Today. The newspaper and Ipsos, a global research and marketing firm, conducted two polls at the same time from May 18-21 and said that the “credibility intervals,” which are similar to margins of error, are plus or minus five percentage points for the teachers survey and 5.6 percent for the survey of parents.

It is not possible to know how school districts would be affected if 1 in 5 teachers did not show up to reopened schools, because schedules and attendance expectations will probably be different in the fall to comply with social distancing requirements.

School districts are racing to complete plans for the fall semester but are also factoring in contingencies: full-scale openings, no openings or some hybrid.

Many districts have said they are considering having students come in on some school days but not others so that social distancing rules inside classrooms can be respected. An outbreak of the coronavirus on any school campus could lead to a full-scale closure.

In the polls, about two-thirds of both teachers and parents said they support having students go to class up to three days a week and staying at home to work remotely the other days. Such a schedule could mitigate a loss of teachers unwilling to return to school.

Schools across the country — and much of the world — closed this spring as the coronavirus spread.

Some, such as in South Korea, have started reopening, but very few have in the United States, and, according to UNESCO, nearly 70 percent of the world’s students are still being affected by school closures. That is down from close to 95 percent of the world’s students a few months ago.