Overall, 5,800 teachers and other staff were required back to prepare for in-person learning. Among this larger group of teachers, teachers aides and others, 40% did not return.

CPS CEO Janice Jackson said Monday morning she respects that some staff feel trepidation about returning during the pandemic. But she said students are relying on staff to be there for them when they walk into school buildings.

“I have noted that this transition is going to be hard and difficult for everyone, but I am confident about the plans we have put in place,” she said.

Jackson and Chicago public health officials also reiterated their argument that returning to school is safe with the mitigation protocols the school district has put in place. She and Mayor Lori Lightfoot argued it is the right thing to do for students struggling with remote learning.

“We can’t write off the school year, as some have said to me privately,” Lightfoot said. “Writing off a school year is writing off children’s lives.”

Earlier in the morning, the Chicago Teachers Union said it actually expected the number of staff to drop as the week goes on. On a call attended by thousands of CTU members Monday evening, union leaders said many complained about the working and learning conditions they encountered in schools.

The union called on the school district to come to an agreement with them on a number of issues related to reopening. CTU President Jesse Sharkey said the union is still demanding a standard health metric for when it is safe to return and things like mass testing. But he added a new demand.

Sharkey said there should be a way to allow for teachers who want to teach remotely to provide instruction for students who are staying home.

Only about 37% of those who have been offered an in-person option so far are expected back. This includes preschoolers, some special education students and all elementary students. However, the school district is insisting that all staff responsible for these students report to classes, regardless of how many students are there, if any.

“There’s lots of ways that we can make solutions here,” Sharkey said. “But we’re never going to make solutions if the district unilaterally decrees that a whole set of solutions are off limits.

“Otherwise, what’s going to happen is that people who actually have to make the schools work are going to continue to act out their conscience and are going to continue to refuse to under unsafe conditions,” he said.

Sharkey also said that the union could take a strike authorization vote in mid-January if a deal is not reached.

But Jackson held firm that all staff need to come into buildings. While discipline will be handled on a case-by-case, school-by-school basis, she said that the school district is trying to set the stage for a broader return to in-person learning and that it can not have some staff deciding to go into schools and others not.

Sarah Karp covers education for WBEZ. Follow her on Twitter @WBEZeducation and @sskedreporter.