Asian teenagers lead the world in math, reading and science while U.S. students lag behind in the middle of the pack, a study indicates. The 2012 Program For International Student Assessment exam looked at how 15- and 16-year-olds performed on the common core subjects. Students in Shanghai, China, were best, demonstrating subject knowledge and skills equivalent to at least one additional year of schooling compared to students in Europe and the United States. In mathematics, Shanghai teens performed at a level equivalent to more than two years of formal schooling better than students in the state of Massachusetts, PISA said. "The biggest surprise from Shanghai ... was not that students did well on reproducing subject matter content but that they were very, very good in those higher order skills [that reflect] what you can do with what you know," OECD Deputy Director of Education Andreas Schleicher told CNN in an interview for its On China program to be broadcast this month. Test results were announced Tuesday in Paris. While overall global scores in math for all 65 Organization for Economic Cooperation and Development nations in the study fell 0.3 percent, to a mean score of 494, Shanghai students scored 613, an improvement of 4.2 percent from the last survey. PISA conducts its lead survey of educational performance every three years. The two-hour exam was taken by more than 500,000 students worldwide. East Asians dominated, with Singapore, Hong Kong, Taipei, South Korea, Macao, China and Japan, ranked seventh, at the top followed by students in Lichtenstein, Switzerland, the Netherlands, Estonia, Finland, Canada, Poland, Belgium, Germany and Vietnam. Students in the United States failed to place in the top 20 in any category, lagging behind at 36th in math with 481 points, and average scores in reading and science. The United Kingdom ranked 26th with average scores in math and reading, and slightly better test scores in science.