Mayor Lori Lightfoot said Thursday that the city would not add extra school days to make up for possible time lost in a teachers strike, a decision that would break with past practice in school walkouts.

“No. There’s no plan to make up any days,” the mayor told reporters at City Hall. “If you look at the CPS website on contingency plans, there’s zero plan to make up any days that might be lost as a result of a work stoppage. We want to make sure we get a deal done.”

But could Chicago Public Schools or members of the Chicago Teachers Union lose money if those days aren’t made up?

State law requires district calendars include 176 instructional days per school year and a minimum of five emergency days at the end of the year. Those five days can be used to make up days for bad weather or something such as a work stoppage — but they don’t have to.

If a district falls below the required 176 days, it can get flagged by the Illinois State Board of Education for not meeting state statute. But it would take larger and more consistent failures under the state’s current funding formula — which doesn’t rely on attendance anymore — to risk losing state funding, an ISBE spokeswoman said.

Prior to 2017, a district risked losing 1/176th of its state funding for every day it sat below the minimum number of instructional days required.

After the CTU’s 2012 strike, the district made up all those days by shortening winter break, taking away the day off for Presidents Day and adding days at the end of the school year.

This year the district has exactly 176 instructional days, according to an online CPS calendar, so any strike would put the district into violation of state law if no days are made up. But there's still little to no chance that could result in any immediate loss of funding.

Teachers, meanwhile, could potentially lose pay if the eventual settlement with CPS doesn’t include back pay in the form of strike days being added back into the calendar. But in the 2012 agreement and in recent charter strikes, CPS has made up those days and allowed teachers to earn their money back.

CTU President Jesse Sharkey said not extending the school year to make up lost days would break the norm, but he isn’t focusing on that issue.

”This isn’t our decision. We don’t get to make that decision,” Sharkey said. “That’s the way the mayor has chosen to spin this. And it doesn’t make a lot of sense for us to try to second guess that. Our job is to keep trying to negotiate a contract.”