"Today was a good day," said Jennifer Johnson, CTU Chief of Staff.
"We're out here to let everyone know we had a good day," said Sybil Madison, Chicago Public Schools.
The back-and-forth conversation stretched longer into the evening. Teachers and city negotiators are now trying to navigate crucial details.
RELATED: Chicago Teachers Strike 2019: Where to find childcare when schools are closed
"We're still working through our conversations around some of the key issues, like class size and staffing and pay for our experienced educators, like paraprofessional pay," Johnson said.
CPS bargainers said they didn't want to get into too many details lest they hinder progress, but felt encouraged that they are moving in the right direction.
As negotiations continued, the CTU appeared to prepare to increase pressure on public officials as they underwent civil disobedience training.
CTU President Jesse Sharkey was not specific about what kinds of actions or disruptions could be planned, but he did explain how they would look.
"It would look like bringing our case directly to the powerful people, the people who control the purse strings and control the levers of political power that can settle this in a fair way," Sharkey said.
"What we are saying by having civil disobedience training is that we see ourselves as the tip of the spear of the fight for educational justice for the city, and that we're willing to do what it takes, we are willing to put our bodies on the line if necessary, to get what our students deserve," said Jennifer Johnson, CTU Chief of Staff.
Special education teachers rallied to express their frustration over the staffing levels proposals being offered by CPS.
"Something has to be done. There's not enough time in the day for me to do everything I need to do," said Samantha Heatley, special education case manager.
WATCH: CTU special ed teachers respond to ongoing CPS negotiations Thursday
CPS negotiators said they have reached tentative agreements on 80 issues, just not the main ones on class sizes and staffing. The mayor said they have given CTU written offers on those two areas, and are waiting for counterproposals.
"We are bargaining," Mayor Lori Lightfoot said. "It's not stalled, but it's not nearly fast enough to really drive this thing towards a resolution."
But CPS is also stepping up the pressure to get a deal done.
"This cannot go into next week, after next week we have students who will not be able to take the PSAT to qualify for National Merit Scholarships," said LaTanya McDade, CPS Chief Education Officer. "So there's a lot on the table that we have to get some movement."
WHAT IS A TIF, AND HOW MUCH OF THAT MONEY CAN GO TO CPS?
A big sticking point in negotiations is money from what's called Tax Increment Financing, or TIF, funds. Union leaders say the money should go to them, but the city says that's not possible.
Teachers sing, march and protest about Lincoln Yards, a massive North Side development that hasn't even been built yet. So what does it have to do with putting a nurse, social worker in every CPS school?
"If there is a billion dollars for wealthy developers, there needs to be money for schools to get a contract," Sharkey said.
The CTU claims the city gave $1.3 billion to Sterling Bay, the developer of Lincoln Yards. But that's not exactly true. The city did declare the 55-plus acre property a $1.3 billion TIF district. But what exactly is a TIF?
"It initially began as a way to drive economic development into communities that wouldn't otherwise," said Ralph Martire, Center for Tax and Budget Accountability.
Developers don't get money up front. A TIF district works by freezing the properties' tax rate for 23 years. If the value of the property goes up due to redevelopment, the increased revenue covers development costs. In Lincoln Yards' case, it will pay for infrastructure, like new bridges and roads.
"That doesn't mean the taxing authorities lose revenue," Martire said.
Taxing authorities like the city, county and Chicago Public Schools still get their fair share of property tax money. Over 52 percent of your property tax rate goes CPS. Schools can only get more TIF money if a TIF district is declared a surplus.
"It could get to the point where your TIF generates more revenue than what it needs to cover all the projects, then it creates a surplus," Martire explained.
By closing out some TIF districts, Mayor Lightfoot announced a $300 million TIF surplus. Of that, $163 million will go to Chicago Public Schools.
STRIKE COULD IMPACT STUDENT SPORTS
The strike may also prevent hundreds of student athletes from competing in playoff state competitions.
RELATED: Emergency injunction filed on behalf of CPS student athletes as teachers strike jeopardizes state playoffs
More student athletes could be affected as the strike drags on, because a certain amount of games and practice are required to be eligible to compete.
Among the teams impacted is Simeon Career Academy, which hold a 6-1 record. The Illinois High School Association will likely hear the school's appeal later this week.
Twenty-six thousand CPS teachers and 8,000 support staff workers including custodians, special education assistants and bus aides are on strike. It is the first CPS teacher strike since 2012.