Striking Chicago teachers picket today outside Ray Elementary School, where U.S. Education Secretary Arne Duncan sent his children when he was Chicago's schools chief. (Photo: Raiselle Resnick for GothamSchools)

Chicago’s long-threatened teacher strike, which began today, isn’t just about Chicago teachers. It’s also something of a referendum on the current moment in education policy.

Of the many reasons for the strike, three stand out. We explain each one below — and then explain how the strike could evolve from here. In a second post, we’ll explain why the Windy City’s labor conflict matters here in the Big Apple.

1. A new mayor. Chicago teachers have been distressed for several years as budget cuts caused school closures and hundreds of layoffs. Tensions between the Chicago Teachers Union and the city mounted last year when former Obama chief of staff Rahm Emanuel was elected mayor, bringing with him an aggressive approach to cost-cutting, the support of national education reform advocacy groups, and a superintendent who cut his teeth under Joel Klein in New York City. Jean-Claude Brizard quickly earned criticism as “anti-teacher” based on his record in Rochester, N.Y., where 95 percent of teachers gave him a “no-confidence” vote shortly before he departed.

Emanuel immediately announced that he was canceling raises promised to Chicago teachers and requiring teachers to work longer days and years. The extended-day gambit backfired when a state labor board ruled that Emanuel could not unilaterally require that kind of change. But Emanuel pressed on, offering incentives to schools that would add teaching time. He and Brizard also introduced a new rating system for schools, engineered closures and multiple “turnaround” efforts that cost some teachers their jobs, and introduced a new teacher evaluation system without union consent. (WBEZ Chicago has a comprehensive timeline of Emanuel’s education initiatives and how they were received.)

2. A new teachers union. Emanuel’s moves would have angered any teachers union. But since 2010, Chicago’s has one of the most aggressive in the country. That’s when a minority party known as the Caucus of Rank and File Educators, or CORE, took power from the reigning union leadership, which it criticized as complacent on issues of privatization and community engagement. After contract talks failed to satisfy the union this year, its members voted to authorize a strike in June, in a vote with a 91.5 percent turnout rate and a 90 percent approval rate. Since then, the city made several rounds of concessions and reached a deal with CTU about how to extend the school day. But several issues remained unresolved by the strike deadline on Sunday.

CORE started out as a minority party in the union that was organizing with the goal of pushing the union’s agenda to the left. As budget conditions worsened and city officials took an increasingly aggressive tone, the group gained traction with a platform that stood apart from most union leaders’.

The American Federation of Teachers, the national union headed by Randi Weingarten of which CTU is a part, has been willing to collaborate with members of the education reform movement, including President Obama and Mayor Bloomberg. But  CORE urged outright resistance. Its platform echoes criticisms levied by the historian Diane Ravitch, who characterizes Obama and Bloomberg as profiteers who seek to privatize public education and shove teachers and students to the margins.

“What drives school reform is a singular focus on profit,” said Karen Lewis, the party’s presidential candidate, in her acceptance speech after she and other CORE candidates won a come-from-behind election in 2010. In her fiery debut speech, Lewis told the then-superintendent, “You’ve met your match.” Tensions only escalated after Emanuel became mayor last year.

3. A reform movement that left many teachers feeling alienated and angry. As in most contract talks, one big issue in Chicago’s was pay. The union wanted members to get raises that Emanuel had canceled and additional pay for working longer hours. But both CTU officials and Emanuel said on Sunday night that the compensation issues were surmountable.

The real sticking point was teacher evaluations: Chicago has rolled out teacher evaluations that will ultimately be based 40 percent on student performance, and the union doesn’t want student test scores to play any role in how teachers are rated. On Sunday night, Lewis said thousands of teachers could lose their jobs under the new system, which she said could not possibly account for poverty and other issues that students and teachers face.

Holding teachers accountable for how much their students learn is a signature platform of the education reform movement. The Obama administration’s Race to the Top program encouraged states across the country to rewrite their laws governing how teachers are evaluated, hired, and fired, prompting dozens of states to rewrite their laws. Illinois and New York are two of them.

But there are other issues at play, too. The union also wants class size limits added to its contract; currently, Chicago has large classes and only guidelines, not rules, governing their size. And the union also wants teachers who were displaced because their schools closed or lost enrollment to have “recall rights” to claim any new jobs — a pressing issue right now because schools must extend their day by hiring a second shift of educators. It’s not legal for the union to strike over recall rights, but CTU officials say it has to get settled as part of a broad slate of contract issues before teachers will go back to work.

Chicago’s final offer, which the city published after the union turned it down on Sunday, offered “joint implementation” of a new teacher evaluation system, “improved monitoring of class size issues,” and a five-month window for displaced teachers to find new positions before being fired. But it did not dial back the role of test scores in evaluations or introduce recall rights, which Emanuel said would have compromised principals’ ability to choose who is on their staff.

What happens next? The strike seems assured of bringing more attention to the thorny issues that have divided unions and mayors not just in Chicago but across the country — and, potentially, of bringing sympathy to their position. But the strike also gives the Emanuel administration new ammunition to use against teachers and their union in the future.

Ending the strike quickly would be politically expedient for both the city and the union, neither of which wants to be blamed for disrupting instruction, leaving children without care, and potentially costing parents pay or even their jobs. But that doesn’t mean either side is going to cede ground easily. Some components of the teacher evaluation plan CTU opposes are set in Illinois state law, so the city can’t change them. And Lewis has sworn not to return teachers to their classrooms until they have a contract that responds to the union’s complete set of contract demands.

One interesting dimension is the contrast introduced by Chicago’s charter schools, which enroll about 50,000 students and are operating as usual today. It’s the first time that a major city has had a teachers union strike and a large swath of non-unionized schools remain open.

As for today, union and city officials are back in contract talks after a night’s break. Meanwhile, Chicago teachers are picketing outside their schools today while classes are canceled for about 350,000 students. This afternoon, they will rally at their union headquarters.

And parents who expected to send their children off for the second week of school today must fend for themselves. The city is encouraging parents to handle chid-care on their own but has opened about 150 school buildings and other sites to families with no other options. Non-union Chicago Public Schools employees and volunteers are staffing them in an arrangement that the union has warned will expose children to strangers. Students will do independent reading, arts and crafts, and athletic activities, but they cannot be taught without certified teachers on hand. The city is also deploying hundreds of police officers to the temporary “Children First” sites, picket lines, and places where out-of-school students might congregate.