The author of this essay suggests that, Under No Child Left Behind (NCLB), reliance solely on numerical measures, principally math and reading scores, to evaluate performance has corrupted schooling. Educators responding to the need to devote more time to math and reading has led to reductions in the time spent on social studies, science, art, music, physical education, cooperative learning, and other character-building activities. Reductions have been most severe for disadvantaged students who are most in need of a balanced curriculum. Schools now focus on "bubble" students (those just below the proficiency point) to the detriment of students who are far behind or already above proficiency. Accountability for an unreliable single test score results in arbitrary classifications of some fine schools as failing, and some poor schools as adequate. The author claims that some schools manipulate data--for example, by opportunistic assignment of students to subgroups where they do the least harm to school ratings. Defenders of NCLB are quick to denounce teachers for such tactics, suggesting that if teacher quality were higher, teachers would get high test scores without teaching to the test or engaging in other shortcuts to high test scores that do not reflect true learning. In this article, the author discusses how experience with quantitative measurements in other sectors can inform the use of high-stakes test scores in education.