Evolution (?) of Arne Duncan's position on the use of standardized tests for teacher evaluation

Arne Duncan’s position on the use of value-added test scores seems to have changed in the last two years. In August, 2010, he seems to be saying that test score gains are a measure of teacher effectiveness. In May, 2011, he seems to want to use value-added measures as part of teacher evaluation, and in February, 2012 he seems to be against the whole idea.

August, 2010: Effectiveness = gains on tests (value-added)?
“U.S. Secretary of Education Arne Duncan said Monday that parents have a right to know if their children's teachers are effective, endorsing the public release of information about how well individual teachers fare at raising their students' test scores.” (http://articles.latimes.com/2010/aug/16/local/la-me-0817-teachers-react-20100817)

May, 2011: Use both observations and value-added measures.
“Together with you (teachers), I want to develop a system of evaluation that draws on meaningful observations and input from your peers, as well as a sophisticated assessment that measures individual student growth, creativity, and critical thinking. States, with the help of teachers, are now developing better assessments so you will have useful information to guide instruction and show the positive impact you are having on our children.”
http://www.ed.gov/blog/2011/05/in-honor-of-teacher-appreciation-week-an-open-letter-from-arne-duncan-to-americas-teachers/

Feb, 2012: Don’t use value-added measures?
“Teacher evaluation should never, ever be based on test scores.” (Arne Duncan, http://www.thecrimson.com/article/2012/2/7/ed-school-arne-duncan-education/)

Note that if value-added measures are used even for just part of teacher evaluation, this means that we will have to test students in both the fall and spring, to control for gains and losses over the summer. This doubles the already massive amount of testing to be done.