NEW YORK (NewsNation Now) — It’s mid-September, and the return to school is still a coronavirus-related work in progress in districts across the country.

New York City provided an example Thursday of just how fluid the situation is. In a blow to Mayor Bill de Blasio’s effort to make New York one of the few major U.S. cities to hold in-person classes, plans are changing again.

Instead of students who want in-person instruction returning Monday, it will be a rolling start, beginning with pre-K. Many students in the nation’s largest district won’t see the inside of a classroom until October.

“We’re doing this to make sure that all the standards we’ve set can be achieved,” de Blasio said during a City Hall press briefing, stressing that the 11th-hour decision is being made in the interest of safety, designed to make sure schools are properly staffed and ready for students. The city says 42% have chosen online learning this year, a number that’s up about 15% in the past two weeks.

It was teachers who were first to note problems with New York’s back-to-school plan and threatened a strike, forcing the first rollback in the start date, along with concessions from the district. Many then suggested the administration wasn’t living up to its end of the bargain, and that a pledge to hire 2,000 additional staff to kick-start the school year wasn’t enough in the face of the COVID-19 pandemic. The city has now promised to more than double that number.

Teachers union president Michael Mulgrew joined the mayor in making the announcement.

“We are protecting our schools, our children and their families,” he said. “And ourselves, against this horrendous situation that we face which is known as our pandemic.”

It’s a similar situation in districts across the country, as parents and students in several cities rally for a restart of in-class instruction and districts work to follow where the science leads. It’s a moving target.

The state of Indiana reports hundreds of early teacher retirements.

Belinda Fairchild has been a teacher for 37 years but tells NewsNation the pandemic was just too much. She has family members who are at high risk and fears bringing the virus home to them.

“We did have some staff members from the high school who contracted COVID in May,” she said. “They’re younger than I and they had a tough time recovering from it.”

Chicago Public Schools reports eight staff members have died since the pandemic began. Hundreds more have tested positive for COVID-19. The district hopes students can return to classrooms in November.

In some cases, it seems smaller schools are faring better, as staff across the country are forced to get creative. Outdoor classrooms are being used in Grandville, Michigan and a hybrid learning model is in place in Owensboro, Kentucky.

In Greenleaf, Wisconsin, just outside Green Bay, children are back in classrooms and working parents say they’re already breathing easier.

“I felt relieved here because we have small class sizes,” said Nicole Tumo, a mother of four. “We’re a small school and we have the space to spread out. If we were in a bigger district with a school that had more students, maybe then I would feel differently.”