The 2015 PISA (Program for International Student Assessment) test results have just been released. While U.S. students scored at about the same rates in reading and science literacy (scores that are nothing to cheer about), math scores have declined. Key findings for the U.S. are available online from the OECD, the administrator of the test; statements and slides from the acting NCES Commissioner can be perused; and here is a full report. A partial answer for why the U.S. is always mid-range in the world rankings can be found in this article The 2015 PISA Results: What Do They Mean?
U.S. Students’ Scores in Reading, Science, and Math Are Flat Or Lower