The superintendent of the largest school district in Minnesota has had the same discussion with his colleagues on repeat, roughly every three hours, all week: Which surrounding schools have announced a shift to distance learning? How did they make that decision? How many staff are left in his Anoka-Hennepin schools — and is it enough to sustain in-person learning for another couple days?

"Each district has a different situation," Superintendent David Law said. "But the first thing to shut us down is staff absences ... The decision point is 'How short-staffed are we and for how long?'"

There's no statewide threshold to trigger a shift to remote learning — those decisions are left to individual districts this school year. Over the summer, the state health and education departments released a guide of best practices to prevent COVID-19 in schools, based on the Centers for Disease Control and Prevention guidance. Those recommendations encourage leaders to prioritize in-person learning while working to protect the health and safety of students, families and educators.

Despite the commitment to keep students in school, widespread staff and student absences — exacerbated by the rapid spread of the omicron variant—have forced several Minnesota districts into remote learning. Minneapolis schools go online starting Friday with a plan to return Jan. 31. Many other districts, including Osseo, Rochester, Shakopee, Prior Lake and Richfield made similar decisions this week.

School buildings, however, will keep their doors open with staff on-site to offer a space for students who want or need a place to attend class online or complete remote assignments. State law specifies that if a district moves to online learning, an in-person option and meals must still be offered.

Gov. Tim Walz said Monday that districts' decisions are "really, really difficult" and Minnesotans are going to "have to be flexible" as schools move into distance learning for a few weeks at a time.

"The next few weeks are going to be pretty tough," Walz said.

Rosemount-Apple Valley-Eagan schools have so far held off on a move to distance learning, but they would likely start by moving high school students to remote learning first, said district spokesman Tony Taschner.

That shift could free up substitutes to fill in for staff absences for younger grades, potentially enabling elementary and middle schools to remain in-person, Taschner said.

The district's transportation department is stretched especially thin now, Taschner said, but may benefit from being able to tap bus drivers from districts that have gone to distance learning.

More relief may come for districts that have adopted a shorter five-day isolation period for those who are asymptomatic or have resolving COVID-19 symptoms, based on CDC guidance.

"For some districts, that's the difference between being able to maintain in-person learning or moving to online," said Scott Croonquist, executive director of the Association of Metropolitan School Districts.

Even so, Law said it's impossible to fully predict how long teachers in his north metro district, which serves about 36,000 students, will be sick.

"Every day at 3 in the afternoon, I look at the numbers of who is predicted to be gone tomorrow," Law said. "That number goes up by 25 to 50 percent overnight."

Law said his colleagues have said schools generally lose the ability to cover classrooms when the rate of absent licensed staff reaches 20%. In Anoka-Hennepin schools, the student absence rate has jumped up to 20% on some days. It's normally between 5-8%, Law said.

"I would argue that at that point, we're still better off in school," Law said. "If we get down to having one-fourth of our students not in class consistently, it's pretty tough to move forward."

In a message to families and the Minneapolis school board Tuesday, a day before announcing the shift to remote learning, Superintendent Ed Graff said each choice about changing learning models comes with "its own set of consequences."

"Every decision is seemingly an impossible trade-off," he said. "We have many perspectives on what we should have done and what we should be doing."

Croonquist, of the association of metropolitan school districts, said schools are all just trying to hang on. District leaders are in "constant communication" with each other and with local health officials, he said.

Though some districts have been hit harder and earlier by the latest COVID-19 surge, he said, schools across the state are stretched increasingly thin.

"We have a lot of districts right on the brink [of online learning] right now," he said. "They're just barely holding on."