CHICAGO (CBS) — Chicago Public Schools teachers returned to schools today, after the district reached a tentative agreement with the Chicago Teachers Union over COVID-19 safety measures for the district amid the latest surge of cases.

Students are expected to return to in-person learning tomorrow.

READ MORE: Chicago Weather Alert: Snow Totals From Lake Effect Snowstorm

The deal establishes metrics on how individual schools will switch to remote learning if there’s an outbreak among staff or students, as well as provide for more thorough contact tracing and enhanced COVID testing layers.

The full union still needs to vote to approve the deal before it is ratified.

Mayor Lori Lightfoot said she believes it will help keep teachers, students, and their families safe during the most recent surge of cases, which has been fueled by the more contagious Omicron variant. The mayor said she’s hopeful CTU rank-and-file will ratify the deal this week.

“I want to say that CPS put a great proposal on the table that both bargaining teams discussed in detail throughout the day,” Lightfoot said Monday night. “Now, we will be able to get teachers back in the classroom tomorrow, and our kids back on Wednesday.”

It’s not clear if the students will have to make up any of the five days of classes that were canceled after CTU voted last week to have teachers work remotely, or if teachers will get paid for the days they weren’t in the classroom.

The Chicago Teachers Union House of Delegates voted 63-37 Monday night to suspend a remote work action the union took last week. CPS responded by canceling classes altogether.

“This has been a very unpleasant experience,” CTU President Jesse Sharkey late Monday. “The CTU felt like we were asking for a set of reasonable things – obviously as teachers who have been in buildings since the beginning of the school year.”

The suspension of the remote work action comes as the rank-and-file union membership votes on a proposed agreement with the Chicago Public Schools on COVID-19 safety.

“We know that this has been very difficult for students and families,” Lightfoot said. “Our goal throughout this entire process was to both get our students back to in-person learning aa quickly as possible, and prevent work disruptions for the rest of the school year.”

READ MORE: Mayor Lightfoot Added To Lawsuit Over Removal Of Christopher Columbus Statue In Little Italy

The tentative agreement includes safety metrics that would shift individual schools to remote learning for five days if at least 30% of teachers are absent for two days because of COVID-19, and the use of substitutes can’t get that absence rate under 25%; or if 40% of the school’s students are required to quarantine.

The deal also calls for an opt-in testing program, with the district and the union agreeing to work together to increase student participation in testing to 100% by Feb. 1.

CPS also will offer new incentives to encourage substitute teachers to accept assignments during the pandemic, and provide KN95 masks for students and staff.

“It’s not an agreement that had everything. It’s not a perfect agreement,” Sharkey said. “But it’s something that we can hold our heads up about – partly because it was so difficult to get.”

Kozlov asked Mayor Lightfoot if there are any guarantees that rank-and-file teachers will remain on the job in person if they end up voting the proposal down.

“I’m going to emphasize the positive,” Lightfoot said. “I think it’s meaningful that the House of Delegates voted to end the work stoppage – and certainly my hope is that the rank-and-file teachers, who will be voting, we’re told, sometime later this week, will ratify the agreement.”

This comes after four days of no classes for CPS students and a contentious battle between the Mayor’s office and the union. A fifth day, of course, will be added Tuesday. On Monday morning, a car caravan assembled as a show of solidarity for the Chicago Teachers Union in the Loop – causing gridlock for others around the lunch hour Monday.

“Basically, the mayor is being relentless; but she’s being relentlessly stupid. She’s being relentlessly stubborn. She’s relentlessly refusing to seek accommodation,” CTU President Jesse Sharkey said Monday morning. “And we’re trying to find a way to get people back in school.”

Over the weekend, a Chicago Public Schools spokesperson said the district had agreed to provide KN95 masks to students and staff and to allow schools to reinstate health screeners. The district rejected the union’s proposal of an opt-out testing program, which would allow schools to test all students unless parents denied consent.

Before Monday night, Mayor Lightfoot had not publicly taken questions on the teachers’ ongoing work stoppage since Thursday. In a weekend tweet, she thanked Gov. JB Pritzker for agreeing to sell CPS 350,000 rapid antigen tests after being widely criticized for not responding to the state’s offer of COVID help for weeks.

MORE NEWS: Illinois DCFS Director Marc Smith On Hot Seat Before State Lawmakers Over Lack Of Beds And Foster Homes For Kids, Other Issues

It is unclear now how many days, if any, students will have to make up as they’ll have missed five days. It is also unclear whether teachers will be paid for any of the days they missed.