The Times has sued the Los Angeles Unified School District to obtain its teacher ratings that are calculated using students' standardized test scores.

The nation's second-largest school district calculated confidential "Academic Growth Over Time" ratings for about 12,000 math and English teachers two years ago. Last year, the district issued new ratings to about 14,000 instructors that were also viewed by their principals.

The scores are based on an analysis of a student's performance on several years of standardized tests and estimate a teacher's role in raising or lowering student achievement.

The Times filed a California Public Records Act request for the scores and teacher names shortly after they were released, but district officials have declined to release teacher names, saying it could be an invasion of privacy.

The newspaper earlier calculated and published its own teacher ratings based on student test score data released by the district.

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