The education reformer obsession of trying to evaluate teachers based upon student test scores has proven to be a failure, time and again. Starting with Bill Gates, Michael Bloomberg, and Eli Broad, and joined in by the mass media the education reformer holy grail was to link teacher ability with high-stakes testing. However, the American Statistical Association found that a teacher only accounted for between 1% and 14% of a student's growth score. In fact, in the Sherri Lederman case the judge found the New York State high-stakes test to be "junk Science"! Combine that with the rushed and faulty roll out of the age inappropriate Common Core standards and it sparked a parent uprising with 22% of the State's students "opting out" of the test.
The only reason most states have a linking of a teacher's evaluation to a test is because of the 4 billion dollar bribe the Obama Administration dangled at states who were in a recession. It was called "Race to the top".
To receive the money, New York State received 700 million dollars, the States had to have some sought of linkage between a student's test grade and a teacher's evaluation. Therefore, to try to meet the federal requirement and to make the teacher evaluation quantifiable, the State came up with a complicated mathematical equation called "Value Added Method" or VAM for short. As in most states it was"garbage in, garbage out"and most educators referred to the VAM as "junk Science". This was clearly exposed in the Lederman lawsuit. Despite the fact that the maximum a teacher's influence on a child's growth was 14%, New York State arbitrarily made it 40% and then raised it to 50% this year when Governor Andrew Cuomo was upset over the lack of "ineffective" teachers under the old rubric.
A severe backlash resulted by educators and with dropping ratings and under pressure from disgruntled parents, Governor Cuomo changed course 180 degrees and there is now a four year moratorium for grades 3 to 8 but not for high schools where Regents scores can still be used to determine a teacher's evaluation, at least until the first teacher gets an "ineffective". Since the inappropriate use of test scores in the Lederman case as precedent, I expect all those test-based "ineffective ratings" would be thrown out. Because as everybody knows you can't measure quality with a ruler or a test score for that matter.