The Chicago teachers' strike is well into its third day and an end to the walkout is not looking likely. After the latest session of talks ended Tuesday night without a deal to bring teachers back to work, the head of the Chicago Teachers Union describes their progress as "glacial".

Talks between Chicago Public Schools officials and the union ended around 8 p.m. Tuesday, after negotiators spent all day trying to hammer out an agreement on a new teacher evaluation system.

Karen Lewis of the Chicago Teachers Union said in an interview that the union has only signed off on six of 49 articles within the contract.

Chicago Board of Education President David Vitale claimed Tuesday night that there was agreement on more than just six issues, but the union was not officially signing off on those matters to make it appear publicly as if the two sides are further apart.

Vitale said the district has presented an updated proposal to the union, in an effort to address their concerns on the teacher evaluation system, as well as other issues.

"I would not say that we came to agreement on the fundamentals of all of that, but there are proposals that they did give to us which are included in this comprehensive proposal, and there are changes in our own proposals that we've made to them," Vitale said.

Vitale said the district has also asked for a written response to their contract proposals, or a comprehensive counter-proposal from the union.

"When we receive a written response, or a written proposal, we will sit down and meet with them," Vitale said.

Earlier Tuesday, Vitale had predicted a deal could be reached by the end of the day.

But, at a downtown rally attended by thousands of teachers and their supporters, Lewis said it was "lunacy" to think a deal could be reached that soon.

The union has been resisting the district's push to implement a new teacher evaluation system that was part of a state law passed in 2010. Lewis called the evaluation system the district wants "extremely, extremely untested."

Teachers do not want the evaluation system to rely heavily on students' standardized test scores.

"We want an evaluation system. The one we have is clearly not good," Lewis said. "We want an evaluation system that gives us the opportunity to actually develop and grow as teachers. That is extraordinarily important to us. ... But this system is not the one."

CTU teachers have been on strike since Monday, and have been negotiating with the Emanuel administration on a daily basis, with no deal in sight.

As teachers continue to strike, many students go without their education while students in other states continue to potentially excel in subjects.

"This is not the behavior of a group of people that are serious about the interests of our children. It is time for us to get serious." Vitale said.

CPS has opened 144 of its buildings during the strike for half-days so that students can occupy their time with activities and eat breakfast and lunch. Still, parents of Chicago school children have been left scrambling to find all-day supervision for their kids.

The teachers union and CPS have agreed on a number of issues, including salary and a longer school day.