Public school students are graded and tested all the time. Schools are scored too — California rates them in an annual index.

Not so with teachers.

Nationally, the vast majority who seek tenure get it after a few years on the job, practically ensuring a position for life. After that, pay and job protections depend mostly on seniority, not performance.

That’s from The Los Angeles Times, which recently published a fascinating article about evaluating teachers (read it here). They used a statistical method known as “value-added analysis” to rate teacher effectiveness in Los Angeles public schools. They explained that, “Value-added analysis offers a rigorous approach. In essence, a student’s past performance on tests is used to project his or her future results. The difference between the prediction and the student’s actual performance after a year is the ‘value’ that the teacher added or subtracted.”

The Times obtained seven years of math and English test scores from the Los Angeles Unified School District and used the information to estimate the effectiveness of L.A. teachers — something the district could do but has not.[…]

Among the findings:

• Highly effective teachers routinely propel students from below grade level to advanced in a single year. There is a substantial gap at year’s end between students whose teachers were in the top 10% in effectiveness and the bottom 10%. The fortunate students ranked 17 percentile points higher in English and 25 points higher in math.
• Some students landed in the classrooms of the poorest-performing instructors year after year — a potentially devastating setback that the district could have avoided. Over the period analyzed, more than 8,000 students got such a math or English teacher at least twice in a row.
• Contrary to popular belief, the best teachers were not concentrated in schools in the most affluent neighborhoods, nor were the weakest instructors bunched in poor areas. Rather, these teachers were scattered throughout the district. The quality of instruction typically varied far more within a school than between schools.
• Although many parents fixate on picking the right school for their child, it matters far more which teacher the child gets. Teachers had three times as much influence on students’ academic development as the school they attend. Yet parents have no access to objective information about individual instructors, and they often have little say in which teacher their child gets.
• Many of the factors commonly assumed to be important to teachers’ effectiveness were not. Although teachers are paid more for experience, education and training, none of this had much bearing on whether they improved their students’ performance.

I highly recommend reading the whole article. A question for teachers and administrators who read my blog: what do you think of value-added analysis, and using this as a tool to evaluate teachers? The article concedes that it should not be the sole method of evaluation, but suggests that it would be beneficial if it made up 30-50% of a teacher’s review.