Will the Chicago teachers strike have national consequences?

On Thursday, the Chicago Teachers Union and the city again failed to reach a deal over teacher evaluations and other issues, sending thousands of Chicago teachers back to the picket lines for the fifth day in a row on Friday. Meanwhile, 350,000 Chicago kids are spending another day out of class. As the union and Mayor Rahm Emanuel continue to spar over salary, laid-off teachers' benefits and the mayor's education reform agenda, the first teachers strike in 25 years is likely to alter the often-controversial national conversation around how to improve the nation's schools.

Two recent polls show that for at least this first week, more Chicago residents support than oppose the strike. Forty-seven percent of Chicago voters supported the strike, according to a Chicago Sun-Times poll; another survey commissioned by a political columnist on Wednesday found that 55 percent of voters backed the teachers' decision to hit the picket lines. And Chicago parents are even more in favor of the protest. In the second poll, 66 percent of respondents who had children attending the city's public schools said they were for the strike.

On the national level, however, the issue has brought together the unlikely pair of the New York Times editorial page and Republican nominee Mitt Romney, who have both condemned the strike as unnecessary and bad for the city's schoolchildren. Education Secretary Arne Duncan, treading carefully between the Obama administration's own education reforms and the Democrats' need to maintain political support from teachers unions, said in a statement that "both sides" in Chicago have kids' best interests at heart.

While local support is far more important for the Chicago Teachers Union (CTU) and its bargaining clout, the national conversation about the strike could have implications for the education reform movement, which has split Democrats in recent years. President Barack Obama has embraced reforms that demand big concessions from unions, including evaluating teachers based at least in part on whether their students' standardized test scores improve under their instruction. The Chicago strike is unusual because its leaders say teachers are not primarily upset over so-called bread-and-butter issues like compensation and benefits, but rather reforms like the test-based evaluations and privately run charter schools that drain students—and money—away from traditional schools. (Most charters are nonunion.)

The strike could be a good opportunity for teachers unions to build support for their contention that standardized testing narrows the curriculum and is an unreliable and unfair way to judge teachers, and that high-poverty schools need more money and social services to help their kids succeed. But it could also backfire, bolstering state lawmakers' and mayors' arguments for the reform.

So far, CTU President Karen Lewis has made the argument that "value-added" test-based judgments of teachers are particularly unfair in struggling Chicago public schools, where 80 percent of schoolchildren qualify for the free or reduced federal lunch program. "This is no way to measure the effectiveness of an educator," Lewis said last weekend in announcing the strike. "Further, there are too many factors beyond our control which impact how well some students perform on standardized tests such as poverty, exposure to violence, homelessness, hunger and other social issues beyond our control."

But others disagree with this line of reasoning. Amy Wilkins of the advocacy group Education Trust believes Lewis is contributing to "ugly myths" that poor kids cannot do well at school, rhetoric that may be alienating some union-friendly liberals who might otherwise support the strike. (See Nicholas Kristof.) While value-added scores can be unreliable, they measure student improvement on tests over time, not the students' initial skill level, meaning even the most underprepared students should be able to improve under a good teacher.

"People will take their cues from the outcome of this drama," Wilkins said. But even if public opinion sways toward the union, Wilkins says she doubts momentum will slow for new test-based evaluations.

Nancy Waymack of the National Council on Teacher Quality agreed that test-based teacher evaluations "aren't going away any time soon," pointing out that nearly half of all states mandate student test scores in teacher evaluations. As of last year, teachers can be dismissed based on those evaluations in 14 states.

On Thursday night, the teachers union said it was willing to have value-added test scores count for 25 percent of teacher evaluations, with an additional 10 percent coming from teachers' evaluations of student performance, to meet Illinois state law's requirement that at least 30 percent of evaluations must come from student performance. The city and union were still struggling over pay, however, with the union wanting a 5.8 percent raise to make up for Emanuel's yanking of a promised 4 percent raise last year, the Huffington Post reported.

Union supporter and education historian Diane Ravitch, however, argues that the strike is not about evaluations but rather two very different visions for education. "If the mayor wins, it will be perceived as a victory for a continued assault on teachers and their unions and an endorsement of school closings and privatized charters," she writes. "If the teachers win, which is a long shot, the children of Chicago might get smaller classes and a better curriculum."

Still, even if the union wins in Chicago, it's unclear if that would boost its cause nationally.

"You've got everybody across the political spectrum ... people on the left and the right putting blame for the strike on [the union's] shoulders," said Michael Petrilli, an education expert and executive vice president of the Thomas B. Fordham Institute, an education think tank. "In Chicago they'll get something out of it, but nationally I don't see how unions will get anything but a black eye."

Petrilli added: "I think this is going to embolden some of the mayors who want to push for some of these reforms."

And the failure of union supporters to oust Wisconsin Gov. Scott Walker after he sharply curtailed collective bargaining rights for teachers last year may have given public officials more confidence.

Some education experts believe it's too soon to tell how the strike will play out in the court of national opinion, or whether it will even matter to the larger changes taking place in public education.

"I would probably be skeptical that any one local strike or local negotiation will have a big impact nationally," said Tim Daly of The New Teacher Project (TNTP), a nonprofit that advocates for more rigorous teacher evaluations. Daly thinks that if neither side wins a major concession from the other, then the strike is "unlikely to change the conversation too much nationally."