Chicago Teachers Union President Karen Lewis made her first appearance at Tuesday's rally in front of Chicago Public School's headquarters.
She spoke to the thousands of teachers, parents and supporters who filled the streets this afternoon.
"When they start talking about laying off our members, what they're really talking about is increasing the class sizes of our children," Lewis proclaimed.
SEE MORE: Thousands attend downtown teachers rally
The CTU says today's negotiations focused on teacher evaluations-- an issue both sides are having a hard time agreeing on. Teacher's evaluations are partly based on standardized test scores.
The union argues that part of the Board of Education proposal could displace roughly 6,000 teachers.
"We are concerned about any evaluation system that would put 28% of our members in harm's way of being dismissed," Lewis continued. "And that is just not an acceptable number."
American Federation of Teachers President Randi Weingarten also addressed the marchers on Tuesday afternoon from a riser in the middle of the street. She told the teachers she was proud to be with them. Weingarten wore a red T-shirt that read "Stand with the Chicago Teachers Union."
Marchers cheered, chanted and carried signs that read "On Strike." They booed when Chicago Teachers Union President Karen Lewis mentioned Chicago Mayor Rahm Emanuel and chanted "Rahm Emanuel has got to go." Earlier in the day Emanuel reiterated that he considered it a "strike of choice."
The Chicago Board of Education hopes there will be a compromise that leads to an end to the strike.
"We're working hard every day, hopefully not too many days to resolve this as quickly as possible," Chicago Board of Education Vice President, Jesse Ruiz said. "We still believe we could do this while having our kids in the classroom, having the teachers in the classroom where they belong."
Chicago Teachers Union members went on strike from Chicago Public Schools on Monday.