In 2010, the Los Angeles Times outraged educators nationwide with an ambitious and never-before-attempted project rating 11,500 teachers in Los Angeles by mining student test scores.

The ratings purportedly reflected the value teachers added to their students’ academic performance. The newspaper accorded teachers the designations of least effective, less effective, average, more effective, and most effective.

At the time, many states had convened blue-ribbon panels to improve schools and most seized on teacher quality as the weak link.

In rolling out its ratings, the LA Times explained:

Seeking to shed light on the problem, 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.

The Times used a statistical approach known as value-added analysis, which rates teachers based on their students' progress on standardized tests from year to year. Each student's performance is compared with his or her own in past years, which largely controls for outside influences often blamed for academic failure: poverty, prior learning and other factors. Though controversial among teachers and others, the method has been increasingly embraced by education leaders and policymakers across the country, including the Obama administration.

In a recent piece in Chalkbeat, writer Matt Barnum looked at the response to the LA Times story, writing:

In 2010, then-Secretary of Education Arne Duncan praised the publication of teacher ratings. He used federal carrots and sticks to encourage states to use student test scores as part of how teachers are judged, a policy most states adopted.

But since then, states like New York and Virginia have barred the public release of this performance data, while media organizations have increasingly shied away from publicizing them. The new teacher evaluation systems have run into political challenges, and in some cases not had the hoped-for effects on student performance. And the federal education law passed in 2016 specifically banned the secretary of education from pushing teacher evaluation rules.

In revisting the LA Times value-added ratings in its newsletter last week, the National Education Policy Center notes, "The debate over publicizing value-added scores, so fierce in 2010, has since died down to a dull roar...But schools across the U.S. still use the approach to evaluate teachers. Value-added might have a lower media profile than it once did, but it remains a prominent reality for many thousands of American teachers."

One problem in trying to calculate a teacher’s contribution to a child’s learning-- or failure to learn -- is that education continues well beyond the six hours a day, 30 weeks a year that students spend in their classrooms. Education takes place in children’s homes, communities, summer camps and after-school activities.

The New York Times Magazine makes that point today in an excellent piece on whether good teaching can be taught, chronicling a dynamic but demanding Atlanta Public Schools principal as she attempts to reshape the teaching force at her struggling school, Peyton Forest Elementary, over a two-year period:

In the piece "Can Good Teaching Be Taught?", writer Sara Mosle reports:

While teacher effectiveness may be the most salient in-school factor contributing to student academic outcomes, it contributes a relatively small slice — no more than 14 percent, according to a recent RAND Corporation analysis of teacher effectiveness — to the overall picture. A far bigger wedge is influenced by out-of-school variables over which teachers have little control: family educational background, the effects of poverty or segregation on children, exposure to stress from gun violence or abuse and how often students change schools, owing to homelessness or other upheavals.

The piece – which I recommend you read – concludes:

Teaching does matter, and it can improve. But there is little evidence — at least to date — that it can counter the effects on children of attending neighborhood schools that remain racially and economically isolated.