The task seemed straightforward enough: Students taking part in a recent international test were asked to review drawings of five triangles with varying angles and midpoints. Then those teenagers were to read over a paragraph describing the characteristics of a particular triangle and, finally, choose the triangle that fit the description. Of the students from industrialized nations who took that exam, the Program for International Student Assessment (PISA) 62 percent received full credit for answering the question correctly. Yet the assignment befuddled a greater percentage of test-takers from the United States, of whom only 46 percent received full credit. That poor showing repeated itself throughout the problem-solving and mathematics-literacy sections of PISA, whose results were released here and in other locations around the world last December 2004. The exam showed U.S. 15-year-olds lagging behind their peers from other industrialized nations in those areas. By some measures, American students fared better on a second, equally scrutinized international test released a week later: the Trends in International Mathematics and Science Study (TIMSS). That exam showed U.S. 4th and 8th graders scoring above international averages in math and science, and minority groups improving. To some education experts, though, the U.S. performance on the two international exams reinforced their belief that American students suffer from an inability to perform complex reasoning and mathematical assignments--the kind they are likely to encounter in college and the workplace.