Lisa Fleisher:

New York City on Friday released internal rankings of about 18,000 public schoolteachers who were measured over three years on their ability to affect student test scores.
The release of teacher’s job-performance data follows a yearlong legal battle with the United Federation of Teachers, which sued to block the release and protect teachers’ privacy. News organizations, including The Wall Street Journal, had requested the data in 2010 under the state Freedom of Information Law.
Friday’s release covers math and English teachers active between 2007 and 2010 in fourth- through eighth-grade classrooms. It does not include charter school teachers in those grades.
Schools Chancellor Dennis Walcott, who has pushed for accountability based on test scores, cautioned that the data were old and represented just one way to look at teacher performance.
“I don’t want our teachers disparaged in any way and I don’t want our teachers denigrated based on this information,” Mr. Walcott said Friday while briefing reporters on the Teacher Data Reports. “This is very rich data that has evolved over the years. … It’s old data and it’s just one piece of information.”

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