Matt Di Carlo is a careful social scientist. He combs through the data on teacher evaluation and tries to understand whether they make sense statistically. In his latest blog, he reports that the the results so far seem to show that most teachers are getting very good ratings. This is a huge disappointment to the corporate reformers, because they were counting on the new evaluations to discover vast numbers of “bad teachers” and those teachers would be fired.

He cites an article in Education Week which found that “in Michigan, Florida and Georgia, a high proportion of teachers (more than 90 percent) received one of the two top ratings (out of four or five). This has led to some grumbling among advocates and others, citing similarities between these results and those of the old systems, in which the vast majority of teachers were rated ‘satisfactory,’ and very few were found to be ‘unsatisfactory.'”

In other words, the advocates believe that when students get low scores, it is the fault of bad teachers, so there must be lots of bad teachers out there.

The District of Columbia, as Di Carlo shows, just redesigned its ratings so that more teachers would fall into the “ineffective” range. How disappointing for reformers if they can’t find and fire large numbers of bad teachers! Think of all the job openings for the trainees of The New Teacher Project or TFA! All those little groups of new teachers funded by the Gates Foundation can cheer as the median age of teachers drops lower and lower, and inexperience becomes the norm.

Much as I admire Di Carlo, I disagree with him about teacher evaluation by test scores. I think it is clear that it will cause teaching to the test, cheating, gaming the system, avoiding the neediest students, and narrowing the curriculum. I think it is JUNK SCIENCE.

Value added assessment was cooked up by economists and statisticians to measure productivity, and it is out of place in education.