Because you didn't read the article. The US and international scores are from PISA tests. This is mentioned in the first sentence of the article. http://en.wik

Because you didn't read the article. The US and international scores are from PISA tests. This is mentioned in the first sentence of the article. http://en.wikipedia.org/wiki/Programme_for_International_Student_Assessment http://en.wikipedia.org/wiki/Programme_for_International_Stu... The state data in the article comes from NAEP... which is a national US test