Here’s what it’s found already by doing so:

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.

The public ought to know these numbers and it’s good to see the LAT flexing its muscle here to provide them.

Ryan Chittum is a former Wall Street Journal reporter, and deputy editor of The Audit, CJR's business section. If you see notable business journalism, give him a heads-up at rc2538@columbia.edu.