Updated at 4:16 a.m. ET: LOS ANGELES -- An agreement was reached Tuesday night to end the crippling strike at the ports of Los Angeles and Long Beach, according to Los Angeles Mayor Antonio Villaraigosa.

The announcement came just hours after federal mediators arrived at the port of Los Angeles, called on by Villaraigosa to help resolve a strike that has idled most of the docks at the ports for more than a week.

The eight-day labor clash cost Southern California an estimated $8 billion, including lost wages and the value of cargo rerouted to other ports over the past week, according to Reuters.

Los Angeles and Long Beach together account for nearly 40 percent of all U.S. container imports.

George Cohen, director of the Federal Mediation and Conciliation Service, and Scot Beckencaugh, deputy director for mediation services, arrived Tuesday night to begin talks between shipping and union officials, the mayor's office announced.

It was unclear whether a vote had been planned prior to their arrival or what role they played in the developments late Tuesday.

The mayor flew back from a trip abroad to help bring an end to the work stoppage, staged by clerical workers who use computers to help track the progress of shipments into and out of the nation's busiest port complex.

Villaraigosa, a onetime labor activist who had been in Latin America pitching Southern California's port operations to manufacturers, shippers and retailers there, arrived at the harbor at about 11 p.m. Monday, joining the negotiations in the hope of brokering a deal.

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Tuesday morning, he said, he called to request help from a federal mediator. The mayor said he also discussed the matter with California's two Senators, Dianne Feinstein and Barbara Boxer, and that he has placed a call to the White House.

Despite claims by both sides that they had made significant concessions in the talks so far, Villaraigosa said at a news conference that neither had moved on issues of top concern to the other.

In particular, he said, the union, which is worried about outsourcing jobs, might need to compromise on other issues to get movement on its top priority.

As the talks dragged on, the clerical workers continued to walk picket lines.

Each side blamed the other for the slow pace of negotiations.

John Fageaux, spokesman for Local 63 of the International Longshore and Warehouse Union, said his organization had backed down on a demand that the companies re-hire 51 positions that the union said had been outsourced, but received no productive response from the employers.

But Stephen Berry, an attorney representing the shipping companies, said those jobs had never been outsourced in the first place. Instead, he said, they represented positions that had been held by clerical workers who were not replaced after they retired.

For his part, Berry said that the shipping companies had agreed to one of the union’s key demands, saying that they would hire certain temporary workers from the union’s hiring hall, rather than going to outside contractors.

But he said that the union was not satisfied with that offer. He said the union failed to recognize that the economy had still not recovered from the boom years.

The stoppage at 10 of the port's 14 terminals will not affect holiday shipments, experts said, because the toys, books, electronics and clothes aimed at the gift market arrived months ago.

But Villaraigosa said it affects about 20,000 truck drivers, retailers and others who are awaiting shipments for upcoming seasons.

The ports of Los Angeles and Long Beach together handled more than $400 billion in goods arriving or leaving the West Coast by ship last year, according to Reuters. Experts say the ports directly or indirectly support 1.2 million Southern California jobs - workers involved in moving freight to or from the shipping complex. 

NBCLosAngeles.com's Sharon Bernstein and Annette Arreola and Reuters contributed to this report.

NEWS ANALYSIS 

CHICAGO – Now that the Chicago teachers strike has ended, it is inevitable that people will try to figure out who won and who lost. But more might be gained if we went beyond that.

What if more time were spent thinking about what students and the country gained from this strike, because it focused attention on the debate over teacher evaluations, the weight that is given to standardized tests and the growing demand for education reform?

Broken system
A lot has been said about the need to get rid of bad teachers and the union that protects them. The truth is union leaders will tell you they don’t like bad teachers, either. But the union would argue that it’s not their job to weed out bad teachers. Rather, they say, school leaders should do a better job identifying bad teachers and weeding them out.

In Chicago, according to a 2009 report by the New Teachers Project, 91 percent of teachers were rated “superior” or “excellent” by school principals. Out of the nearly 30,000 teachers in the city public school system, only a small fraction received an “unsatisfactory” rating. But with student achievement at such a low level, clearly something must be wrong with how the evaluations were being done.

So this is a good time to consider who’s responsible, in addition to teachers, for what happens in school. I spoke with several teachers on the picket line over the past few days who were concerned that they didn’t have books to start the school year. Why isn’t everyone up in arms about that? 

Other teachers told me that they were assigned to classrooms outside of their area of expertise. One woman on the picket line told me she had taught English last year but she was trained to be a gym teacher. “I just tried to help out where there was a need,” she said. 

Biggest losers of Chicago's teachers strike? The students, critic says

Does anyone really believe she is the best English teacher for Chicago kids?  

Should those students and that teacher be judged on how well she’s able to prepare them to take a standardized test?

And don’t think this is an isolated, one-of-a-kind situation.  It’s not.  You will find similar stories in schools all across this nation.

In Finland, where students far out perform American kids, they don’t take standardized tests at all. Students are measured by how well they do on their classroom work and drills.

There is a collective national will in Finland to educate all students, and there’s a plan to succeed. Finland starts by hiring the best and the brightest to teach. Finnish teachers are required to have a master’s degree and teachers come from the top 10 percent of college graduates. Compare that to the U.S., where 47 percent of America’s teachers come from the bottom third of their class, according to a 2010 McKinsey report.

Chicago teachers agree to end strike, classes to resume Wednesday

Big issue: poverty
Then there’s the issue of poverty and safety and how it affects teaching and learning.

Mayor Rahm Emanuel went to court this week seeking an injunction to force an end to the strike claiming, in part, the walkout was a threat to “public health and safety.”

As many as 87 percent of the public school children come from low-income families, according to figures from Chicago Public Schools.   

More than 90 percent of them qualify for the free or reduced breakfast and lunch program.  For many, school is where they go, not just for an education, but for food. 

It’s also where many children go to feel safe in a city stricken by far too much violence.

The teachers hit the picket line demanding money, a fair evaluation system and job security but, they also wanted more social workers in the schools to help them help children who have been traumatized living in broken homes and broken neighborhoods.

According to the Chicago Public Schools Employee Roster, there are 382 social workers in the school district that serves 350,000 students.  If my math is correct, that amounts to about one social worker for every 916 students. 

“That means social workers are doing paper work because they don’t have time to do much of anything else,” said Lorraine Forte of Catalyst Chicago, an independent newsmagazine dedicated to reporting on urban education.  

Education Nation: Get involved in our 2012 summit, Sept. 23-25

Not unique
Chicago’s school problems are not unique.  Poverty, crime and lack of resources affect schools all across the country.

Experts are quick to point out that none of these issues should be used as an excuse for failing to educate America’s children. Teachers, city leaders, policy makers and education reform advocates all agree that these factors also shouldn’t be left out of the conversation. And in fact, they aren’t – but real solutions need to be found.

Chicago has presented an opportunity for the nation to take a closer, more thoughtful look at a multitude of reasons why schools and test scores and graduation rates are lacking.  It might also inspire us to look at schools that are working to see if they could be replicated. 

That’s what we will be doing starting this Sunday when NBC launches its Third Annual Education Nation Summit.  But what’s wrong with America’s schools won’t be fixed if too much time is spent adding up winners and losers from one strike.

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As the dust settles on Chicago's first teachers strike in 25 years, one critic says the biggest loser of the labor standoff is the students.

"This is not the big shake up this school district needed," said Kristina Rasmussen, executive vice president of the Illinois Policy Institute, a conservative think tank. "It goes back to the same system with kids being trapped in schools with little recourse. The students are the big losers."

Rasmussen said several issues that helped lay the groundwork for the strike remain: Most students in Chicago public schools are struggling academically, performing poorly on standardized tests and failing to graduate from high school.

School reformers cheered Mayor Rahm Emanuel's push for longer school days and greater teacher accountability, with job security being tied to student achievement. But teachers were able to soften the review system a bit, while also securing raises and maintaining a decent level of job security.

Chicago strike reveals a broken system

"In his fight with the teachers, he still ends up with a better-functioning school day," said Robert Bruno, a professor of labor and employment relations at the University of Illinois at Chicago.

But Rasmussen believes Emanuel didn't push hard enough.

"He has an opportunity to be a great champion of education reform, but not if he approaches future battles with the same timidity," Rassmussen said.

The proposed contract includes a 7 percent salary increase over three years and a deal where 30 percent of teacher evaluations are based on test scores. While principals will retain hiring power, one-half of new hires must come from a pool of laid-off teachers.

Education Nation: Get involved in our 2012 summit, Sept. 23-25

Emanuel has brushed off questions on how the district plans to pay for the new deal, pointing out “this contract, unlike past, is more frugal than past and yet it ensures that we invest in children.”

The new contract, according to the mayor will add $75 million to the $665 million deficit for the current year. Faced with a $1 billion budget deficit for fiscal 2014, the cash-strapped school system will have to make deeper cuts, including staff positions and closing low-enrollment schools to meet the contract's financial demands, according to NBC Chicago.

Chicago's clash came during a time of heated debate nationwide over how to improve public schools. Democrats and Republicans have blasted unions, as they face steady declines in membership, for backing the status quo.

But during the strike, opinion polls showed most parents and Chicago voters backed teachers and the union, with some parents and students joining rallies and picket lines. The mayor found public favor for his educational reforms, according to local media reports.

"He tried to show that he's tough, and on the side of the school kids and concerned with the parents, which played well," said University of Illinois political science professor Dick Simpson.

Supporters rushed to Emanuel's defense.

"We needed the longer day, we needed more accountability in the schools,” Danny Solis, a Chicago alderman, told NBC Chicago. “The mayor set the tone, it was hard fought.”

Education Reform Now, a group involved in the school reform movement, funded an advertising campaign on television to highlight the mayor's victories in the labor dispute. The ads aired Wednesday morning, claiming the mayor’s successful campaign for change.

Analysts say one figure whose profile was raised by the strike is Karen Lewis, the veteran chemistry teacher, Dartmouth College graduate and new union boss who led the union out on strike, the largest since Detroit public school teachers marched in 2006. 

“She is a creation of the moment and the experience has created a much stronger and forceful Karen Lewis,” Bruno said. "There were tense times and profanity thrown around, but in the end she can thank Rahm every night for making her shine in and through this."

NBCChicago.com's Mary Ann Ahern contributed to this report.

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More than 350,000 Chicago Public School students returned to class Wednesday after seven days off during the city's first teacher strike in 25 years.

"We feel very positive about moving forward," Chicago Teachers Union president Karen Lewis said Tuesday after the union's nearly 800-member House of Delegates voted to end the strike. "We feel grateful that we have a united union, and that when a union moves together we have amazing things happen."

Teachers said they're excited to get back to work after voting on the tentative deal article-by-article. One point even received a standing ovation: the freedom for teachers to create their own lesson plans.

For more on the strike, visit NBCChicago.com

Other highlights of the contract include a 7 percent salary increase over three years and 30 percent of teacher evaluations based on test scores. While principals will retain hiring power, one-half of new hires must come from a pool of laid-off teachers.

M. Spencer Green / AP

Students gather outside Benjamin E. Mays Academy for the first day of school after Chicago teachers voted to suspend their first strike in 25 years.

Jesse Ruiz, vice president of Chicago's board of education, told NBC Chicago the agreement means more time for students in school and a revised evaluation system that hadn't been reviewed in 40 years.

"We need to continue these discussions," Ruiz said. "There are a lot of issues that came up that weren't specific to this contract that talk about the quality of our education system."

Education Nation: Get involved in our 2012 summit, Sept. 23-25

Mayor Rahm Emanuel called the deal "an honest compromise."

"In past negotiations, taxpayers paid more but our kids got less," Emanuel said. "This time our taxpayers are paying less and our kids are getting more." 

The deal still must be voted on by the  union rank-and-file, which could take a couple of weeks. It's expected to move through with no problem.

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Updated at 7:08 p.m. ET: CHICAGO -- Union officials agreed to end the Chicago teachers strike, and classes will resume on Wednesday in the nation's third-largest school district.

The Chicago Teachers Union's House of Delegates -- nearly 800 members -- voted to end the strike during a meeting at Operating Engineers Hall, on the city's south side. After the vote, the delegates came out of the hall singing "Solidarity Forever," the Chicago Tribune reported.

The voice vote -- 98 percent in favor -- comes after delegates had a chance to review a contract proposal solidified over the weekend and means roughly 350,000 Chicago Public Schools students will be back in class after seven days off.

The action, however, does not mean an automatic approval of that contract. Ratification of the contract requires a separate vote from the union's rank and file.

"We feel very positive about moving forward. We feel grateful that we have a united union, and that when a union moves together we have amazing things happen," Chicago Teachers Union president Karen Lewis said shortly after the vote.

"We said that it was time, that we couldn’t solve all the problems of the world with one contract. And it was time to suspend the strike,” she said.

NBCChicago.com's Live Blog coverage of Chicago's historic strike

Union delegate Mike Bochner said “an overwhelming majority” of delegates voted for the strike’s end on a voice vote. “I’m really excited, I’m really relieved,”  Bochner, an elementary school teacher, told The Chicago Sun Times.

Ahead of the vote, hundreds of parents had gathered outside the Chicago Board of Education to stand with teachers.

"Whatever decision they make today on the proposed contract, we're behind them," Erica Clark, a Chicago schools parent told reporters. "Parents are asking for the same things teachers are asking for."

Chicago Public Schools teachers walked off the job on Sept. 10 after more than a year of slow, contentious negotiations over salary, health benefits and job security. The teachers' previous contract expired June 30 and both sides weeks later rejected a report assembled by an independent fact-finder.

Mayor Rahm Emanuel called the work stoppage "unnecessary" and one of "choice."

While leadership on both sides continued the back-and-forth of contract negotiations, thousands of teachers and their supporters for days took to the city streets in a massive show of solidarity.

Education Nation: Get involved in our 2012 summit, Sept. 23-25

On Monday, Emanuel and CPS attorneys filed a request for an injunction to force teachers off the picket lines, claiming the outstanding issues, as publicly stated by the CTU -- teacher evaluations and recalls -- weren't legal reasons for a work stoppage.

A provision added to the Illinois Educational Labor Relations Act last year prohibits teachers from strike on issues unrelated to economic matters; those involving pay and benefits.

A Cook County judge declined the mayor's request to hold a same-day hearing on the injunction request. Instead, that hearing would have been held Wednesday. With Tuesday's action by the House of Delegates, that hearing is no longer necessary.

The proposed contract includes the following:

• The CTU wants a three year contract, which guarantees a 3 percent increase the first year and a 2 percent increase for both the second and third year. It also includes the option to extend the contract for a fourth year with a 3 percent raise;
• CPS will move away from merit pay;
• The board will hire more than 600 additional "special" teachers in art, music, physical education, world languages and other classes;
• One half of all CPS hires must be displaced members;
• CPS will evaluate teachers based on 70 percent "teacher practice" and 30 percent "student growth." Additionally, the first year of implementation will not harm tenured teachers and there is a right to appeal the evaluations.

The strike forced parents to find alternative care for their children. Many said they exhausted available vacation time. Others made use of the nearly 150 "Children First" sites that provided students with alternative programming and meals.

As the strike entered its second week, some frustrated parents became more vocal in their demand that both sides end the stalemate. A small group of parents on Monday marched outside CTU headquarters holding signs that read "If you care about the kids, go back to work" and "350,000 CPS Hostages! Let our children learn" and "Don't say you care, show it!"

NBCChicago.com's BJ Lutz and Lisa Balde contributed to this report, as did NBC's Sevil Omer.

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Updated at 5:45 p.m. ET: CHICAGO -- As Chicago teachers union delegates met Sunday to go over the details of the proposed contract hammered out late Saturday night, some worried the union would not approve the deal.

A faction of the union sees it as a "back room deal" that does not have unified support. While Chicago Teachers Union President Karen Lewis and her team are ready to present the details this afternoon, already there is a vocal faction promising to vote no.   

A source close to the union says late into Saturday night, Lewis' caucus shouted obscenities at her and the other leaders - "You sold out" and "Rahm's getting everything they wanted, what the hell did we get?"   

Lewis, who is exhausted from a tense week, indicated that she's done negotiating and asked "Will my own caucus defy me?"

At the heart of those who oppose this new deal - they feel the negotiating team did not fight for paraprofessionals and special education teachers and students.

Read full coverage at NBCChicago.com

Compounding the delegates anger is today at sundown is the Jewish holiday Rosh Hashanah and many of the Jewish delegates feel pressured to vote  even though  they shouted at Lewis there is "no way to vote on something we haven't seen." 

On the other hand, union members could vote to accept the new contract, ending the city’s week-long teacher strike -- the first one in 25 years -- opening school doors for 350,000 students as early as Monday. But delegates could ask for 24 hours to talk to individual members in their schools before making a decision on what to do next.

“We are a democratic body and therefore we want to ensure all of our members have had the chance to weigh-in on what we were able to win,” said CTU President Karen Lewis. “We believe this is a good contract, however, no contract will solve all of the inequities in our District."

Delegates are not the ones who will sign off on the new contract, union leadership explained. That responsibility remains with the union rank and file.

Negotiators started the day with a vow to remain at the table all day, to hammer out final details in an agreement which could open classroom doors again on Monday.

Related:

"Hopefully we can do it," said CTU Vice President Jesse Sharkey said on Saturday before heading into talks to end the week-long teacher strike. "But like I said, the devil's in the details in the contracts, and we want it in writing."

The talks, which began at 9 a.m. Saturday, took most of the day and were still going on 12 hours later. Both sides are working out the details to a "tentative" contract that could suspend the strike and put students back in class.

Once the language of the contract is decided, it will go to the union's House of Delegates for approval. Both sides have expressed a desire to have the contract ready for approval by Sunday.

Even though an agreement is still being negotiated, Sharkey thinks the strike itself was a victory for his members.

"Educators in the city of Chicago feel like they've had their voices heard for the first time in a very long time," he said. "Frankly we're tired of the political establishment taking credit for every gain the schools make, when we're the ones who do all the work."

Earlier in the day, Mayor Rahm Emanuel had no words about the possibility of an agreement and refused all questions pertaining to the strike as he worked the crowd at the Mexican Independence Parade.

Around the same time in Union Park, an estimated 2,500 teachers and supporters gathered for a "Solidarity Rally."

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Lewis was one of the 20 speakers who took to the stage during the rally and applauded the teachers for standing their ground while reminding them the work was not over.

"We are still on strike," Lewis told the crowd decked out in red. "We have a framework; we do not have an agreement."

On Friday, leaders on both sides of Chicago's teacher strike said they have a "framework" in place to end the stalemate that's embroiled the city and kept students out of classes for a full week.

Chicago's first teacher strike in 25 years could end Sunday if the union's House of Delegates approves that action. The delegates are not the ones who will sign off on the new contract, however, union leadership explained. That responsibility remains with the union rank and file.

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Scott Olson / Getty Images

Chicago Teachers Union President Karen Lewis speaks to supporters Saturday during a rally at Union Park in Chicago, Ill.

CHICAGO -- Thousands of striking Chicago teachers rallied on Saturday to keep the pressure on Mayor Rahm Emanuel to wrap up an agreement with their union to end a strike that has closed the nation's third-largest school district for a week.

The rally brought labor leaders, community activists and teachers to Chicago's Union Park for one of the largest demonstrations against Emanuel's education reforms since the strike began Monday.

"You have proven to the world that you're not going to take it anymore," Lorretta Johnson, secretary-treasurer of the American Federation of Teachers, told demonstrators the day after the two sides reached a tentative labor deal.

See strike coverage and more Chicago news at NBCChicago.com

“We are on strike,” CTU President Karen Lewis told the crowd estimated to be about 25,000 decked out in red. “We have a framework; we do not have an agreement.”

Lewis was one of 20 speakers who spoke at the event, which lasted more than two hours.

Led by Lewis, a former high school chemistry teacher, 29,000 unionized teachers, counselors, nurses and other support staff staged their first strike in 25 years, leaving 350,000 Chicago students with no school this week.

Emanuel angered the Chicago teachers by trying to push through proposals to radically reform teacher performance evaluations and weaken job protection for teachers whose schools are closed or perform poorly academically.

Related:

Emanuel retreated from some of his proposed reforms, although details of what he has agreed to with the union have not been made public. Negotiators for the mayor and the union announced a tentative agreement on Friday that could lead to an end to the strike.

The confrontation has left many Democratic mayors and politicians supporting Emanuel, a former White House chief of staff for President Barack Obama. Other Democrats have sided with the unions, which are major financial supporters of the party and are needed to help Obama win re-election in November.

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Emanuel denied Saturday there had been any pressure from the White House to settle the strike.

"The short answer is no," Emanuel's spokeswoman, Sarah Hamilton, said. "There was no pressure, and no pressure would have worked, because they know that the mayor firmly believes that what we are doing to reform and improve our schools is the right thing."

The union is wary of Emanuel, who has been called a "bully" and a "liar" by Lewis.

Organizers hoped Saturday's rally would rival some of the huge demonstrations last year that protested the efforts of Republican Wisconsin Gov. Scott Walker to curb the power of unions. The Wisconsin protests were unsuccessful but drew tens of thousands of government workers, including teachers.

Activists and supporters from other unions joined the sea of strikers wearing red T-shirts at Saturday's rally.

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"This is not just a Chicago struggle; this is a struggle for workers everywhere," civil rights leader Jesse Jackson said. "You've led a new struggle for courage."

If all goes well in the negotiations between the Chicago School Board and the union this weekend, Lewis said she would ask some 800 union activists on Sunday to suspend the strike and teachers would return to classrooms Monday morning.

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Updated at 7:45 p.m. ET: President of the Chicago school board said on Friday that school negotiators had reached a "framework" agreement with the Chicago Teachers Union on a new contract that will end a strike in the third-largest school district in the nation.

"I am pleased to tell you we have in place frameworks around all of the major issues that should allow us to conclude this process and conclude it in time for our kids to be back in school on Monday morning," school board President Dave Vitale said.

Moments earlier, the attorney for the Chicago Teachers Union said the final deal wasn't done yet.

Read more from NBCChicago.com

"The agreement has not been fully drafted and until an agreement is completed, the House of Delegates will not make a decision on whether to suspend the strike," CTU attorney Robert Bloch told reporters.

The union's delegates still will meet at 2 p.m. as planned, Bloch said, and a report will made to them about the progress of contract talks. Negotiations ended for the day, and Bloch said the two parties hope to have a deal drafted by Sunday. The union's delegates is a larger consultative body than the negotiating team.

"If the delegates so vote, we will suspend the strike and students can return to school on Monday," Bloch said.

Talks are expected to continue at 9 a.m. Saturday.

Chicago Mayor Rahm Emanuel issued a statement:

"This tentative framework is an honest and principled compromise that is about who we all work for: our students. It preserves more time for learning in the classroom, provides more support for teachers to excel at their craft, and gives principals the latitude and responsibility to build an environment in which our children can succeed. Now, our most important work continues: providing every child in every community of Chicago an education to match their potential."

Question at heart of Chicago strike: How do you measure teacher performance?

After a late night and early morning of negotiations, school officials had said they were confidently close to an agreement that would end Chicago's teacher strike over education reforms sought by the mayor.

Sitthixay Ditthavong / AP

Public school teachers rallying at Chicago's Congress Plaza protest against billionaire Hyatt Hotel mogul Penny Pritzker, who is also a member of the Chicago Board of Education on Thursday.

Thousands of teachers walked off the job Monday after months of negotiations failed to result in a new contract, affecting more than 350,000 students. It's the city's first teacher strike since October 1987.

"There were some creative ideas passed around, but we still do not have an agreement," Karen Lewis, the fiery former high school chemistry teacher who leads the union, told reporters. "We're going to go back to our respective shops and do some numbers crunching."

"It was a really, really long night," CPS chief education advisor Barbara Byrd-Bennett told NBCChicago.com. "We believe it was a beneficial night. We are so close I do believe it is very, very possible we could have a deal today."

She said she remained hopeful that students and teachers could return to class on Monday.

theGrio: 'Safe havens' for kids offered during Chicago teachers strike

"I think that we made some pretty good progress," Chicago School Board President David Vitale said on Thursday night. "We're closing a lot of gaps."

'A sense of urgency'
A more recent offer included provisions that would protect tenured teachers from dismissal in the first year of the evaluations.

It also altered categories that teachers can be rated on and added an appeals process. Additionally, evaluations could work on a graduated scale throughout the term of the contract, comprising between 25 and 35 percent of a teacher's total score.

"There's a sense of urgency today,'' said the Rev. Jesse Jackson, who stopped by the hotel where the negotiators were working Thursday and spoke to reporters. A day earlier, he said the two sides were talking past each other. 

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Sitthixay Ditthavong / AP

A large group of public school teachers marches past John Marshall Metropolitan High School Wednesday on Chicago's West Side. Teachers walked off the job Monday for the first time in 25 years over issues that include pay raises, classroom conditions, job security and teacher evaluations.

Updated at 3:31 p.m.. ET: CHICAGO -- Classes for the nation’s third-largest school district were canceled for Friday as the Chicago teachers set out to strike for a fifth day, according to NBCChicago.com.

 Negotiators trying to bring an end to the Chicago teachers' strike had said they were confident an agreement would be reached soon, but union leaders cautioned parents it was "highly unlikely" students would return to school Friday.

Chicago Teachers Union president Karen Lewis said she hoped an agreement can be reached by the end of Thursday, the fourth day of the strike.

Lewis told reporters she doubts teachers would be back in classrooms Friday, but said she's hoping for a Monday return. "Oh, I'm praying, praying, praying. I'm on my knees for that, please," Lewis told NBC Chicago. "Yes, I'm hoping for Monday. That would be good for us."

Chicago Public Schools chief education adviser Barbara Byrd-Bennett was even more optimistic, saying she was trying to get students back in class by Friday.

"The conversation was productive," Byrd-Bennett said on Thursday. "There was steady and substantial movement on key issues around teacher evaluation and layoffs and recall.”

Chicago's teachers in the nation's third-largest school district went on strike Monday for the first time in 25 years in dispute of education reforms sought by Mayor Rahm Emanuel.

For the first time in days, Emanuel's chief negotiator, School Board President David Vitale, agreed with Lewis' summary of the talks. Only 24 hours earlier, Vitale had threatened not to come back to the negotiating table until the union put forward a better offer. 

"We had a very productive evening," Vitale said. "We all go away hopeful that we can go come together on this." 

350,000 kids out of school
With more than 350,000 children out of school, the patience of parents had begun to fray as hopes of a quick resolution to the biggest U.S. labor strike in a year faded. 

Earlier in the day, civil rights leader Jesse Jackson, who is based in Chicago, appeared at the site where negotiations were supposed to take place on Wednesday and said that he had met with both sides separately to urge them to settle. 

Lewis said the progress on Wednesday was on the two most vexing issues -- using student test scores to evaluate teachers and giving more authority to principals to hire teachers. 

 Chicago mayor: Get kids in class during contract talks with teachers

"We made significant progress on the teacher evaluation side of the equation," Byrd-Bennett told NBC Chicago. "Clearly we're remaining consistent with not wanting to lower the standards for our children. ... I think there were really good discussions."

 But Lewis said Thursday, there's still much work to be done.

"We haven't even talked about the professional development side," she said. "We want to make sure this is done right. Doing something fast is not the way to go. Haste makes waste."

The union is concerned that more than a quarter of its membership could be fired because the teachers work in poor neighborhoods where students perform poorly on standardized tests, which Emanuel wants to use to evaluate teachers. 

Lewis also said the union fears Emanuel plans to close scores of schools, putting unionized teachers out of work. 

Lewis led the walkout on Monday of more than 29,000 teachers and support staff, saying the union would not agree to school reforms it considers misguided and disrespectful.

Question at heart of Chicago strike: How do you measure teacher performance?

The dispute jolted the United States, where a weakened labor movement seldom stages strikes and even less frequently wins them. Organized labor has lost several fights in the last year including Wisconsin stripping public sector unions of most of their bargaining power, Indiana making union dues voluntary and two California cities voting to pare pensions for union workers. 

The strike in Barack Obama's home city has also put the U.S. president in a tough spot between his ally and former top White House aide Emanuel and labor unions Obama is counting on to win re-election on November 6. 

Obama has said nothing in public about the dispute, allowing administration surrogates to urge the two sides to settle. 

Obama's own Education Department has championed some of the reforms Emanuel is seeking, and a win for the ambitious Chicago mayor would add momentum to the national school reform movement. 

'Difficult for us to understand'
The city is operating 147 schools with non-union staff to offer meals and "keep children safe and engaged," but only a fraction of parents have been using that option, officials said. 

At Disney elementary school, several dozen strikers with homemade signs targeting Emanuel and school policies picketed in cool, sunny weather on Wednesday. 

 Union leader to Chicago teachers rally: In for the long haul

Kent Barnhart, a music teacher for the past 25 years, said neighborhood parents had been supportive, offering water and opening their homes and even joining picket lines to march. But he said teachers were frustrated with the slow talks. 

"It's difficult for us to understand why they have not truly discussed over the last 11 months things that have been very important," he said of school officials. "It didn't seem like they took it seriously -- really important things like evaluations, health benefits and pay." 

Both sides agree Chicago schools need fixing. Chicago students consistently perform poorly on standardized math and reading tests. About 60 percent of high school students graduate, compared with 75 percent nationwide and more than 90 percent in some affluent Chicago suburban schools. 

The fight does not appear to center on wages, with the school district offering an average 16 percent rise over four years and some benefit improvements. 

More than 80 percent of Chicago public school students qualify for free lunches at school because they come from low-income households. 

NBCChicago.com's Michelle Relerford and Lisa Balde contributed to this report, as did  The Associated Press and Reuters.

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