CHICAGO (CBS) — While the debate over a longer school day in Chicago continued to heat up, the heads of the teachers union and the Chicago Public Schools held a spirited debate Tuesday evening on the future of the school system.

As CBS 2’s Suzanne Le Mignot reports, the forum started with Chicago Teachers Union President Karen Lewis offering a warm greeting in French to CPS Chief Executive Officer Jean-Claude Brizard.

“That’s the benefit of a Chicago Public School education,” Lewis said.

But just moments later, things became heated.

“We’re having a no lie zone! Come on! We’re having a no lie zone,” Lewis told Brizard during the forum, after Brizard mentioned the benefits of a longer school day for students.

Seven Chicago Public elementary schools have voted to have longer school days. In return, through a waiver, each school receives $150,000 to use at their discretion and their teachers get $1,250 bonuses.

“The more schools that do it, the more courageous others get, to say, you know what? I’m gonna do what I think is right for our kids,” Brizard said.

LISTEN: WBBM Newsradio’s Lisa Fielding reports

But Lewis has called the move simple “union busting.”

“We filed an unfair labor practice and we hope the Illinois Labor Relations Board will see the deception that’s here,” she said Tuesday.

Earlier in the day, Mayor Rahm Emanuel praised teachers, while also lauding individual schools for opting for a longer school day.

“We have great teachers. We have great kids. The system is stacked against them from achieving what they need to do,” Emanuel said.

The Chicago Tribune event Tuesday evening brought together a large number of those who work for CPS.

“I work with the kids, I see what their needs are and issues and I want for there to be real change,” CPS social worker Joanne Moore-Fafore said.

Students spoke out too.

“We do care and we are listening and we are paying attention to what’s going on in our school district,” said Trevon Martin, a student at Peace & Education Alternative High School.

Northside College Prep student Devyn Rigsby said, “I believe my education in CPS has been a success because my school focuses on the things that are important to me.”

Martin and Rigsby are among seven people who won a Tribune sponsored essay contest about what makes a CPS school succeed or fail. The seven were chosen from nearly 100 applicants. Each winner got to ask a question at the forum.

Watch & Listen LIVE