In 2008, president-elect Barack Obama declared that preparing the nation for the “21st-century economy”required making “math and science education a national priority.” He later signed legislation that provided incentives for states to adopt common standards intended to increase curricular rigor in these and other subjects. Encouraging more students to take advanced classes seems laudable, but concerns have arisen about the ability of many students to complete such course work successfully.Students in urban high schools are of particular concern. Populated predominantly by low-income and minority students, these schools struggle with two related problems.
First, many students do not earn passing grades in early courses that are thought to be prerequisites for more-advanced subjects.Second, students are at high risk of failing to earn their high school diplomas at all. In fact, only 65 percent of black and Hispanic students graduate high school, with little evidence that the graduation gap between them and white students has changed in the last few decades. One theory for these low high-school completion rates is that failures in early courses, such as algebra, interfere with subsequent course work, placing students on a path that makes graduation quite difficult...