Because the tests are biased? Another good reason, but that’s not where I’m going either.
Surely because the tests do not measure the real authentic impact teachers have on the whole child? Sorry.
Because we are allowing profiteering corporate ed-reformers to build their profits on the backs of middle class teachers? Nope. Not that one either.
Quite simply, after teacher evaluations are done every June, test scores are released in July. What’s the impact of this chronological happenstance? Districts that include student test data in teacher evaluations, either as individual scores or as school-based scores (as my district does), don’t include that data in a teacher’s evaluation until the following year. In other words, a teacher’s test results from this year would impact their evaluations next year. That hardly makes the evaluation an annual one any more.
What happens then for a first year teacher? What happens for a teacher who changes schools from one year to the next? What happens to a teacher who has made amazing strides from the previous year? Whether these events reflect positively or negatively on their evaluations is up in the air. What is clear though is that, with such lag time, the lacking authenticity of such an evaluation system could never result in improved teaching.
What if we judged other people the same way?
What if Michael Jordan were measured at the end of his 1995-1996 season, the 72 win year, by his half-year performance in the 1994-1995 season?
What if Steve Jobs were measured at the end of 2007, the Chinese Zodiac year of the pig and the worldwide economy’s year of the iPhone, by his company’s pre-iPhone performance in 2006?
What if Peyton Manning were measured at the end of his 2012 season, the comeback player of the year (and playoff loss to the Ravens) season, by his spinal fusion season in 2011?
You get the point.
There are many reasons to criticize the use of test scores in teacher evaluations. Lag time, however, from a practicality perspective, should be at the top of the list.