[Update: Much more in three roundups: part 1, part 2, part 3, plus Carol Felsenthal on the national political implications]

If you're wondering why CPS and the Chicago Teachers Union couldn't come to an agreement on the teachers' contract and avoid the strike that started at midnight—when CPS was able to hammer out agreements with two other unions—one answer is that there are a lot of points of disgreement, many more complex than mere salaries.

* Salaries: this gets mentioned first, but it's not necessarily the biggest point of tension between CTU and CPS, and reportedly is very close to agreement if not already done; Emanuel, in a press conference today, didn't mention it as one of the issues still up in the air. Right now, CPS salaries are pretty much in the ballpark of what they've been for decades.

* Health care: Here's what the CPS has offered:

The Board is calling for a modification to the health care plan funding that will freeze all employee health care contributions for single and couple plans with a small increase in family contributions of no more than $20 a pay period in addition to a small increase in emergency room co-pays.  67 percent of all CTU members will not see a change to their healthcare.

[snip]

Like the nearly 40,000 City employees who have already signed up for the Wellness program, the Board is asking teachers to join the program at no cost. Teachers can opt-out of Wellness, and pay a small premium differential.

Like the salaries, Emanuel and city officials have suggested that health care is no longer one of the remaining issues, though it was reported this morning that CTU says it's still in play. CTU wants the current plan to remain as-is; as of late August, CTU hadn't signed onto the wellness plan, which costs $50 a month to opt out of (PDF).

After salaries and compensation, it gets (even more) complex quickly.

* Rehiring of teachers: I mentioned this last week.

* The other big one is teacher evaluation. The short of it's that the Illinois Performance Evaluation Review Act (PERA) was passed in 2010, which implemented a four-category rating system for principals and teachers based in part on "student growth measures," to begin at 300 CPS schools by September 1. This aspect of the strike has been heating up for awhile; back in March, a number of academics suggested that CPS slow down its implementation of PERA:

The proposed rules associated with PERA will not be finalized until April 2012 at the earliest.  Nevertheless, CPS is moving ahead with teacher and principal evaluation plans based on the proposals.  The suggested rules define “significant” use of student growth as at least 25% of a principal’s or teacher’s evaluation in the first two years of implementation, and 30% after that, with the possibility of making student growth count for as much as 50%.

[snip]

Any annual evaluation system should be piloted and adjusted as necessary based on field feedback before being put in place citywide.  In other words, Chicago should pilot models and then use measures of student learning to evaluate the model.  Delaware spent years piloting and fine-tuning their system before putting it in place formally statewide.  Conversely, Tennessee’s teacher-evaluation system made headlines when its hurried implementation led to unintended negative consequences.

Did CTU help negotiate PERA? Yes, as the mayor's said, as part of SB7 negotiations. But PERA didn't specify the details of student growth, just suggestions. The Teachers Union negotiated the actual PERA details with CPS earlier this year, but rejected them:

The new system, Recognizing Educators Advancing Chicago’s Students, will now count student performance as 25 percent of a teacher’s assessment, with the intention to raise that rate to 40 percent in five years.

The CTU released a statement Friday morning expressing disappointment with the decision to move forward with implementing the system without their support.

It's not just a matter of the percentages; CTU has a host of objections to CPS's evaluation plan, 11 by my count, including objections to the number of unannounced teacher-observation visits and "middle of year evaluations": "a principal may issue a MOY Summative Rating to a Teacher, using prior year student learning data, if the teacher’s performance on the Framework would result in an unsatisfactory rating. CTU "objects to this attempt to accelerate the identification of Needs Improvement and Unsatisfactory teachers so that CPS can speed the process of professional development, remediation, and possible discharge."

CTU objected to another aspect of the PERA system (PDF):

The Union is seeking to change the Board’s proposal in which two “Needs Improvement” ratings in a row become an automatic “Unsatisfactory” rating. The Union is concerned that in changing the current “Satisfactory” rating to a “Needs Improvement” designation the Board increases the likelihood that teachers who have an average rating will be unfairly dismissed.

And there's much more where that came from. This may have already been hashed out in negotiations, but it's an example of how fine the details get. And that's just one facet of the negotiations—there are contracts, health care, the implementation of air conditioning in school buildings, and teacher rehirings, and each one of these is ultimately determined by many small sub-agreements.

It's important to keep this in mind. On one hand, it really is an overarching battle that represents more than just CTU versus CPS:

The new vision, championed by Chicago Mayor Rahm Emanuel and U.S. Education Secretary Arne Duncan, who used to run Chicago's schools, calls for a laser focus on standardized tests meant to gauge student skills in reading, writing and math. Teachers who fail to raise student scores may be fired. Schools that fail to boost scores may be shut down.

[snip]

In Chicago, last-minute contract talks broke down not over pay, but over the reform agenda, both sides said Sunday. The union would not agree to Emanuel's proposal that teacher evaluations be based in large measure on student test scores.

But that greater battle manifests itself in seemingly small contract specifications, like whether CPS should do middle-of-year teacher evaluations, how often classroom observations are done, and so forth. The scales may fall on either CPS or CTU, but they're weighted by many details, by lines in the fine print. And the actual timeframe for coming to agreement is surprisingly short:

The August 22 contract bargaining update (PDF) is as good a document as I've seen as far as getting into the details of where CPS and CTU have clashed, though some aspects may have been solved in the meantime. It's a battle, but trench warfare is consists of many, many small battles, inch by inch and bullet-point by bullet-point.

Photograph: Chicago Tribune