Audrey Amrein-Beardsley has started a valuable new blog where she reports the latest news on VAM and interprets the latest research. She is one of our best researchers on the topic and, time and again, she has put a pin in the inflated hope that teachers can be measured like potatoes or corn.

n this post, she dissects Mathematica’s recent research on the value of moving highly experienced NBCT teachers to low-performing schools. She agrees that it makes a difference, but disagrees with the comparison group (which included 20% brand new teachers) and doubts that policymakers would be prepared to carry out the lessons on a grand scale.

What if we found that a class size of 10 was optimum for low-performing students? Would we be willing to implement the policy implications?