The release of a trove of data evaluating New York City teachers on their ability to boost student test scores represents a potentially powerful new tool for parents to assess their children's public schools.
Nationally, teachers unions have staunchly opposed releasing such information, and even some supporters of linking teacher evaluations to student-test scores worry the data could be misunderstood or misused.
If school districts across the U.S. were to begin taking similar actions, it could add to pressure on school administrators to improve or to remove their weakest teachers.
In New York, the nation's largest school system, the teachers' union opposed release of the data on 18,000 public-school teachers. A state court ordered the release in response to a public-records request by The Wall Street Journal and other news organizations. It comes 18 months after the Los Angeles Times published a database, calculated by the newspaper, of teacher rankings in Los Angeles, the nation's second-largest school district.
Lisa Fleisher, WSJ's New York schools reporter, answers frequently asked questions about the city's performance rankings for some 18,000 teachers, which have been released for the first time.
Michelle Rhee, who pushed through a teacher-evaluation system in Washington, D.C., when she headed the district there, said parents should have access to teacher ratings. But she said the data should be released only if they also included such information as principal observations. The information released by New York doesn't include such observations.