Diane Ravitch put it better than I ever could.
According to Politico.com, the U.S. Department of Education will cut federal funding to education schools whose graduates have students who get low scores. This could incentivize education schools to direct their students away from urban districts with high poverty, or from teaching children with disabilities and English-language learners. Researchers have repeatedly warned about the danger of over reliance on test scores for high-stakes decisions. It is always wise to think about unintended consequences.
I want to add that this is the same department of education that drools over Teach for America and policies like this result when we have non eductors carrying out education policies.
I wish Duncan would resign because then we would all truly have something to be thankful for.