Another study highlighting the effectiveness of teachers- this study looked at Teach for America (TFA) Teachers in Miami Schools over the last 5 years and determined that on average students taught by TFA teachers gained 3 months more of math learning in a year than non TFA teachers, but that there was no difference in reading gains. One slightly humorous part of the study was whether other non TFA teachers improved their teaching if there were a cluster of TFA teachers in a school, and the answer was no. Apparently teachers do not absorb teaching ability by proximity – never thought putting the textbook under the pillow and going to sleep was good test prep. Study is here: Miami TFA Study