A great problem in U.S. education is that gifted students are rarely pushed to achieve their full potential. It is no secret that American students overall lag their international peers. Among the thirty-four countries in the Organization for Economic Cooperation and Development whose students took the PISA exams in 2012, the United States ranked seventeenth in reading, twentieth in science, and twenty-seventh in math.
Less well known is how few young Americans—particularly the poor and minorities—reach the top ranks on such measures. The PISA test breaks students into six levels of math literacy, and only 9 percent of American fifteen-year-olds reached the top two tiers. Compare that with 16 percent in Canada, 17 percent in Germany, and 40 percent in Singapore.
Among the handful of American high-achievers, eight times as many kids come from the top socioeconomic quartile as from the bottom. That ratio is four to one in Canada, five to one in Australia, and three to one in Singapore.
What has gone wrong? Thanks to No Child Left Behind and its antecedents, U.S. education policy for decades has focused on boosting weak students to minimum proficiency while neglecting the children who have already cleared that low bar. When...