Recent federal data shows administrators across the country have increased class sizes amid staffing shortages. Salwan Georges/The Washington Post

Nearly 45% of American students started the school year below grade level in at least one subject, and administrators have increased class sizes because of teacher vacancies, according to the results of a federal survey, which shows that the toll of the pandemic goes on.

More than 1 in 4 of the nation’s public schools coped with teacher and staff shortages by creating larger classes, according to data released Thursday by the National Center for Education Statistics, an arm of the Education Department.

“In some schools, even having one teacher down, they’re having to increase their class sizes,” said Chris Chapman, associate commissioner.

School leaders relied on other strategies, too, for making do amid shortages: About 40% said they used their teachers and staff to perform duties outside of their intended role, and 24% shared teachers and staff with other schools.

The shortages had other effects on school life, including disruptions in student transportation, fewer extracurricular activities and a reduction in student services, the data showed. But there were exceptions: One-third of schools reported no negative effects or no vacancies.

In broad terms, the data reflected improvements compared with a year earlier but also showed the fallout of the pandemic continues. NCES Commissioner Peggy Carr said in a statement that it “does signal progress,” while also expressing concern about the large share of students behind academically.

Thirty-seven percent of schools said they were operating with at least one teacher vacancy as of October, and 45% reported getting by with at least one staff vacancy. The data reflected a seven-point improvement in teacher openings and a five-point worsening in unfilled staff jobs that officials said was not statistically significant.

One in 5 schools said they had multiple teacher vacancies, a problem that especially affected large schools, those in high-poverty neighborhoods and those with enrollments primarily of students of color.

Classroom aides were in especially short supply, as were teachers in special education and elementary grades.

The 44% of public school students who started the school year below grade level in at least one class was better than last year’s 49% but worse than the 36 % for a typical school year pre-pandemic. Students lagged most often in English and math.

To help students catch up, 82% of schools reported offering tutoring in one form or another. Experts describe “high-dosage” tutoring as the most effective – with 39% of schools reporting they used that strategy, which involves well-trained tutors working with extremely small groups of students several times a week, over an extended period.

High-dosage tutoring was used at roughly the same share of schools a year ago.

The survey was conducted among 1,421 public schools in mid- to late October as the new school year was underway. It is labeled experimental because it uses an innovative approach to produce a real-time look at COVID-19’s effect on K-12 public schools.