Schools across the country have faced no shortage of challenges since the pandemic. Students are behind academically. Cases of misbehavior are up. Students are absent far more frequently than before.

But there is another problem that has left some school districts scrambling. Teachers are also missing more school.

Teachers typically receive paid sick days and a small number of personal days. Over the 2022-23 school year in New York City, nearly 1 in 5 public schoolteachers was absent 11 days or more, an increase from the previous year and from before the pandemic. In Michigan, roughly 15% of teachers were absent in any given week last school year, compared with about 10% in 2019, researchers found.

More recently, teacher absences forced a school in Ohio to close for a day, and left high school students in Massachusetts to gather in the cafeteria during class time with little supervision.

“The proof in the pudding is how many people have exhausted their leave and are asking to take days off that are unpaid,” said Jim Fry, the superintendent in College Place, a small district in southern Washington state. “That used to be a really rare occurrence. Now it is weekly.”

Making matters more difficult is a national shortage of substitute teachers, which many educators say has worsened since the pandemic. Schools serving low-income areas are the least likely to be able to find enough substitutes, research has shown.

Not all districts have experienced a rise in teacher absences, but those that have point to trends that reflect the broader American workforce.

Employees in many occupations are taking more sick days since the pandemic. Women — who make up the vast majority of the teaching workforce — may also be juggling more child care, as children stay home from school or from day care more frequently. (Mothers are 10 times as likely as fathers to take time off work to care for a sick child.)Employees are also putting more focus on mental health. That is especially relevant for teachers, who have faced increased demands and political pressures over the past four years, while being paid less than similarly educated professionals and having less flexibility to work remotely.

“Exhaustion is hitting them,” said Ian Roberts, the superintendent in Des Moines, Iowa, which has recorded about 300 daily teacher absences this school year, up from about 250 last year.

Teachers, who get built-in breaks throughout the year and during the summer, have at times faced scrutiny from parents for missing school. For example, parents in Newton, Mass. are seeking damages for a teachers strike that led to 11 days off school this winter, and teachers unions were criticized for their role in prolonging school closures during the pandemic. Research shows that a large number of teacher absences can have a negative impact on student learning.

Yet many teachers say they do not like to miss school, in part because it takes significant work to prepare for and catch up from any absence.

“It’s easier just to go in, push through it,” said Tracey Bolton, a second-grade teacher in the Houston area, who said she reluctantly missed school in November with an extreme case of congestion and fatigue.

When teachers do miss work, there often are not enough substitutes available to fill in. In Des Moines, officials can typically find substitutes for a little more than half of the 300 daily absences.

The shortage of substitutes has grown more acute since the pandemic, experts say, because fewer people are entering the teaching profession compared with a decade ago, and there has been more teacher turnover in recent years.

As schools turn to long-term substitutes for unfilled positions, that leaves fewer substitutes available for days when teachers take off, said Tuan Nguyen, an associate professor at Kansas State University, who has studied teacher shortages nationally.

The pool of substitutes has also changed, educators say.

Some substitutes were reluctant to return after the pandemic closures; others took different jobs and never came back. The pay for substitutes, which averages around $20 an hour, is less competitive in a strong economy.

When no substitute is available, remaining teachers often have to do double duty — taking extra students in their classroom, or covering another class on their break — which can lead them to request days off in the future. Sometimes reading tutors or other specialists fill in, which means that extra support sessions — a priority to make up for pandemic learning losses — are canceled that day.

“I think this is having a huge impact on our ability to rebound” from the pandemic, said Amanda von Moos, executive director of Substantial Classrooms, a nonprofit that has sought to improve training and support for substitute teachers.

To reduce the daily scramble, the Sacramento, California, school district recently raised its substitute teacher pay to $355 a day, or about $54 an hour, one of the highest rates in the country.

But that hasn’t solved filling substitute spots in schools that serve some of the lowest-income areas. A study out of Chicago found that paying substitutes up to 50% more to work at hard-to-staff schools can be an effective incentive.