Sarah Wysocki is a Washington, D.C.-area teacher whose career was jeopardized in 2007 by an assessment tool called IMPACT, a data-backed approach to weeding out low-performing teachers. Wysocki was fired from her job after receiving a low score based on IMPACT’s algorithm, which promised to fairly evaluate teachers. But IMPACT was imperfect in that it couldn’t measure the human factors that go into teaching and learning (such as struggles students might be facing at home), so O’Neil characterizes it as a “weapon of math destruction.”