Althoug his news is from USA, it will add to controversy around school league tables and such.
From NYT, Big Study Links Good Teachers to Lasting Gain, by Annie Lowrey:
Elementary- and middle-school teachers who help raise their students’ standardized-test scores seem to have a wide-ranging, lasting positive effect on those students’ lives beyond academics, including lower teenage-pregnancy rates and greater college matriculation and adult earnings, according to a new studythat tracked 2.5 million students over 20 years.
And some sobering remarks:
Still, translating value-added scores into policy is fraught with problems. Judging teachers by their students’ test scores might encourage cheating, teaching to the test or lobbying to have certain students in class, for instance.
“We are performing these studies in settings where nobody cares about their ranking — it does not change their pay or job security,” said Jesse Rothstein, an economist at the University of California, Berkeley, whose work criticizing other value-added assessments unions frequently cite. “But if you start to change that, there is going to be a range of responses.”
I personally would propose an alternative way to assess school teachers: by their students’ performance at the next stage of education. For example, the best criterion to judge a GCSE level mathematics teacher is to look at numbers and academic performance of those his/her students who choose Mathematics/Further Mathematics as an A Level subject.