The breakthrough experiment in New Haven offers a glimpse of an education future that is less rancorous. It’s a tribute to the savvy of Randi Weingarten, the president of the American Federation of Teachers and as shrewd a union leader as any I’ve seen. She realized that the unions were alienating their allies, and she is trying to change the narrative. New Haven may be home to Yale University, but this is a gritty, low-income school district in which four out of five kids qualify for free or reduced-price lunches. Eighty-four percent of students are black or Hispanic, and graduation rates have been low. A couple of years ago, the school district reached a revolutionary contract with teachers. Pay and benefits would rise, but teachers would embrace reform — including sacrificing job security. With a stronger evaluation system, tenure no longer mattered and weak teachers could be pushed out.