Since Mayor Bloomberg announced plans to “turn around” dozens of struggling schools during his State of the City speech in January, the city has hammered out specifics while holding two rounds of raucous meetings at each of the schools that could be overhauled.

Meanwhile, community members, politicians, and union officials have argued against turnaround at rally after rally — even as the city’s plans evolved. On Thursday, they will air those arguments one more time as the Panel for Educational Policy — which has never rejected a city proposal — sits down to hear public testimony and then vote on 26 turnaround plans.

In two posts, we will summarize how the city got here, what turnaround entails, and what could happen after Thursday. First, some recent history:

What exactly is turnaround, anyway?

Turnaround is one of four federally prescribed school overhaul strategies that cities can adopt to qualify for School Improvement Grants. The SIG program was developed to entice states and school districts to improve the lowest-performing 5 percent of schools after U.S. Education Secretary Arne Duncan committed to funding overhauls. The program has gotten mixed reviews across the country but still has sent school districts into a frenzy trying to win scarce funds, which can amount to millions of dollars per school for three years.

If districts want the funds, they must select one of the four strategies for each school on the list. They can close the schools and disperse their students; partner them with nonprofit groups or turn them into charter schools under “restart”; add new resources and programs under “transformation”; or choose turnaround.

Turnaround is the most aggressive strategy and requires that a school’s principal and programming be changed. In the most controversial requirement, it also mandates that at least half of teachers be replaced. This requirement has made turnaround highly controversial in many districts that have tried to use it.

In the version of turnaround that New York City has developed in an effort to follow rules set out in its contract with the teachers union, the schools would be closed and reopened immediately. A team of administrators and union members would rehire a portion of teachers using a process outlined in the contract’s 18-D clause.

Why does the city want to use turnaround?

The initial impetus for the turnaround plan, which Mayor Bloomberg announced during his State of the City speech in January, was pragmatic: The city wanted to be able to receive federal School Improvement Grants for the schools without adopting new teacher evaluations, which was a requirement for the less aggressive overhaul strategies.

The switch was also political: Bloomberg said he was forced into the plan because the union refused to agree on new evaluations. (In fact, the city had backed out of negotiations about evaluations in the 33 schools in late December, then struck an agreement in February on the main issue that had impeded a deal.) Announcing the turnaround plan allowed Bloomberg to appear tough on the union and sound like he had moved closer to his oft-stated goal of being able to low-performing weak teachers.

But city officials have also argued that turnaround is also the fastest way to help the schools improve because it would allow them to shake up their teaching staffs overnight. Here’s what we reported when Bloomberg vowed to go through with the turnaround plans even after the city made progress on teacher evaluation negotiations:

Bloomberg said the aggressive overhaul strategy was necessary because no teachers would be removed from schools because of low scores on the new evaluations for at least a year and a half.

“It would be unconscionable for us to sit around for two years and do nothing, so we’re going to use the 18-D process,” he said, referring to a clause in the city’s contract with the teachers union that the city says allows turnaround’s rehiring process.

Department of Education officials have made educational arguments for the changes at public hearings in the last month. They say an aggressive change could be successful at jolting schools into improvement where other efforts have fallen short.

Why these schools?

Schools have taken a circuitous path onto Thursday’s PEP agenda. All sit on the state’s list of “Persistently Lowest-Achieving” schools, which was first generated in January 2010 and updated in December 2010 in accordance with guidelines set out by the U.S. Department of Education. Schools landed on the list if they had the lowest test scores of all schools receiving Title I funding, which goes to schools with many poor students, or if their graduation rate was under 60 percent for three straight years.

At the time that the lists were compiled, the city’s graduation rate was under 60 percent, and many high schools were added to the PLA list. In 2010 and 2011, the city began overhaul strategies at 33 of the schools but halted them after the breakdown in teacher evaluation talks in December. When Bloomberg announced the turnaround plan in January, 27 of the schools remained on the list, but the city added six new schools to replace others that it opted not to propose for turnaround, including two that were already slated for closure.

The list of low-performing schools had not been updated in more than 16 months, and some schools had shown improvement, often by crossing the 60 percent graduation rate threshold. Last month, the city removed seven schools from the list that had received A’s and B’s on their most recent city progress reports, leaving the 26 whose turnaround proposals are set to go before the Panel for Educational Policy.

Why is the PEP involved?

Since 2009, when the state law about the city’s school governance system was revised, the panel has had to listen to public comment before deciding on city proposals to close or site schools. The panel is only deciding about whether to close the schools, not whether the turnarounds will get federal funding; that decision is up to State Education Commissioner John King, who has said he wouldn’t finish evaluating the city’s applications until next month. The city has said it would go through with the overhaul strategy even if King does not sign off on the federal funds, although officials have signaled that they do not think that outcome is likely.

What does the teachers union think about turnaround?

For many reasons, the United Federation of Teachers is livid about the city’s turnaround plans. The union has long opposed school closures and has even sued to stop them in each of the last two years. Second, the turnaround closures are especially galling to the UFT because Bloomberg blamed the schools’ struggles on teachers at the schools, rather than on dysfunction in the school organizations, which the city has cited in other school closures. Department of Education officials have dialed down that rhetoric in the months since Bloomberg’s announcement, but the original branding still smarts.

In addition, the turnaround process that the city devised strikes, at least in ideology, at two concepts that the union holds sacrosanct: that layoffs should happen according to reverse seniority, and teachers should not be blamed for low academic performance at schools with many high-needs students. Many of the turnaround schools have large numbers of English language learners and students who entered already far below grade level.

And, perhaps most important, the city is blaming turnaround on the union’s recalcitrance in teacher evaluation talks. But the union called for mediation to smooth talks back in December, and the city demurred, even after an agreement on the sticky issue of appeals for low-rating teachers. An evaluation deal would have allowed the schools to be switched back into less aggressive overhaul processes that do not require any teachers to be displaced, an outcome that seems less likely with every day that preparations for turnaround are underway.

The union’s resistance hasn’t come in the form of organized protests. UFT President Michael Mulgrew has petitioned King not to approve the federal funding for the city, and individual schools’ union chapter leaders spoke out at closure hearings. But the larger effort is likely to be happening behind the scenes, where union lawyers are sure to be going over the department’s adherence to procedural rules with a fine-toothed comb. Any missteps would be fodder for a legal challenge.