Millions of kids are about to head back to school, but students, teachers, administrators and parents still don't have a clear picture of how it's going to work.

The big picture: Even the best-laid plans for in-person classes will likely be full of holes, because the coronavirus will make the even the simplest, most intuitive routines extremely difficult — or impossible. And schools will be trying to figure out new structures basically on the fly, with everyone's health on the line.

Instruction: Social distancing at school means less group work, more lectures, and no contact between students and teachers — all in classrooms that were not designed to keep 20-plus kids anywhere close to six feet apart.

• “They were kind of thinking of it in terms of, 'We'll just make the classes smaller.' The problem with that is that they don't have the teachers for that or the classrooms for that," said Jori Krulder, a high school teacher in California.

Meals: "Our cafeteria was already crammed to capacity before the pandemic," said Aaron Phillips, a third grade teacher in Amarillo, Texas.

• That means breakfast and lunch may have to be in classrooms, which raises new questions about cleanliness and extra work for teachers.

Health care: Temperature checks may be frequent. But a majority of schools no longer have a full-time nurse on site, which makes monitoring student and staff health impossible for some areas.

• "[Schools] are going to need the expertise of trained medical personnel on staff," said Melissa Perry, a public and occupational health researcher at George Washington University.

On top of all of that, teachers predict it'll be difficult to get kids — young and old — to maintain six feet of distance and keep masks on.

• "You can paint arrows on the floors, but you can’t make kids not run over and jump on each other and hug each other in the hallways," Krulder said.

What we're watching: All of this planning may get tossed out if coronavirus cases escalate in a community and force schools back to remote learning — which presents its own challenges for both families and teachers.

The bottom line: Schools are opening back up the same way they closed down in the spring: in a frenzy where nobody knows what to expect.

• "This is not me teaching," fifth grade teacher Katie O'Connor said in a viral video in which she rearranged her classroom to meet social distancing standards. "This is not how I want to go back, and I want go back so bad."