Annual Rate of Growth in Student Achievement in Math, Reading and Science in 41 U. S. states, 1992-2011
No.
1
Maryland
3.33% of a standard deviation
See "Is the U,S, Catching Up?" by Eric A. Hanushek, Paul E. Peterson, and Ludger Woessmann for methodological details. 25% of a standard deviation equals approximately one year's worth of learning