For years, the secrets to great teaching have seemed more like alchemy than science, a mix of motivational mumbo jumbo and misty-eyed tales of inspiration and dedication. But for more than a decade, one organization has been tracking hundreds of thousands of kids, and looking at why some teachers can move them three grade levels ahead in a year and others can’t. Now, as the Obama administration offers states more than $4 billion to identify and cultivate effective teachers, Teach for America is ready to release its data.

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