SF Chronicle 

Knowledge is power, but it is not always welcome. The Los Angeles Times just completed an extensive study of how individual teachers have fared at raising their students' math and English test scores in the state's most populous city. The raw data have been available to the L.A. Unified School District for years, but it never bothered to crunch those numbers, let alone share them with parents. The Times has pledged to publish its ratings of 6,000 elementary school instructors. 

Reaction of the local teachers union? It has called for a "massive boycott" of the Times. 

So it goes in California education, where even the most modest attempt to hold teachers accountable encounters fierce resistance from teachers unions. Earlier this year, the unions successfully leaned on their friends in the California Legislature to defeat a bill (SB955, by Sen. Bob Huff, R-Glendora) that would have allowed districts to consider factors other than seniority in teacher layoffs. Proposals to create merit pay, loosen tenure rules, expand inter-district transfers or allow more innovation through charter schools are reflexively denounced by the unions as attacks on a noble profession and the many dedicated teachers whose heroic efforts are underpaid and underappreciated. 

All of us know, from our experience as students and parents, how a special teacher can perform magic on an individual or even an entire class. The Times identified one such teacher from the poorest corner of the San Fernando Valley whose fifth-grade students consistently made striking gains from their fourth-grade scores on standardized tests. Students from the same neighborhood who had a teacher down the hall, in the same school, consistently slipped in math in their year with him. 

Do you think parents might want to have access to that information? I certainly do. So does Arne Duncan, President Obama's reform-minded secretary of education, who asked, "What is there to hide?" 

The union argument is that the tests are flawed, and an attempt to link them to teacher performance is "an irresponsible, offensive intrusion into your professional life that will do nothing to improve student learning," as A.J. Duffy, president of United Teachers of Los Angeles, told the Times.

 Admittedly, students' performance on a standardized test is a limited window into a teacher's effectiveness. But it is a window worth opening. The Times analysis uses what is known as a "value added" statistical approach: looking at a student's past scores to project his or her future results. The difference between the projection and the student's actual results is considered the "value" the teacher added or subtracted. 

This methodology is neither radical nor irresponsible. Its tracking of individual students takes into account the cultural or socioeconomic factors that might otherwise penalize teachers who work in the most challenging classrooms. California and other states competing for Obama's Race to the Top grants have agreed to measure their teachers this way as a condition of their application. 

Jack O'Connell, the state's superintendent of public instruction, said student scores should be one of "a multitude" of elements in evaluating a teacher. 

"Should it be a factor? - yes," said O'Connell, a former teacher, a Democrat and a usual ally of the unions. "Should it be the exclusive factor? - in my opinion, no." 

I asked him whether those teacher ratings should be available to the public. His answer: yes. 

"The more information parents have - we all have - the better off the system is," O'Connell said in a phone interview. 

I put the same questions to Carlos Garcia, San Francisco's schools chief, who has been aggressive in trying to identify and help underperforming teachers. Garcia, like O'Connell, suggests that test scores should only be "a percentage" of a teacher's evaluation. 

"I'm not sure what good it does to publish it for everyone in the world to see," said Garcia, who added that he did not believe that test scores "should ever be used to beat up teachers." 

But Garcia does not dismiss the value of such ratings. In fact, San Francisco has been using test scores at the school-site level to help identify teachers who are achieving gains in the classroom and others who might need mentoring or other professional development.

"Teachers want to learn from other teachers," he said. 

Garcia's strategies include treating teachers as professionals and approaching parents with respect - and to engaging them as partners in the education of their children. Greater transparency about those classroom-by-classroom scores would advance, not undermine, those worthy objectives. 

Parents in Los Angeles should be thanking - not boycotting - the Times for providing them with this limited but important insight into teacher performance. And parents in San Francisco and everywhere else in the state should be pushing school administrators to make this data available to them.