Valerie Strauss solved an interesting question. Why did Secretary Duncan recommend that states limit testing time to not more than 2% of class time?
He got the idea from John King, who is slated to be Interim Secretary after Duncan leaves government. John King was Commissioner of Education in New York, where he proposed a 2% limit on testing time.
That worked out well. Twenty percent of the eligible students (220,000) students opted out of the testing in 2015.
Turns out that 2% is a very large number of hours.