The pack at the top includes South Korea, Finland, Singapore, Canada as well as Hong Kong and Shanghai in China.
Education Secretary Arne Duncan says America has to "deal with the brutal truth." Calling the results "an absolute wake-up call," Duncan says the U.S. has to "get much more serious about investing in education."
The gap between the highest performing countries and the United States was large. Students in Shanghai, on average, scored 56 points higher in reading than the 500-point average reached by U.S. students. Shanghai students also posted the highest score in math, with an average of 600 points. That was 113 points higher than the U.S. average.