> when you normalize the results between the countries, adjusting for the relative poverty of the students taking the PISA tests, the U.S performs significantly better, ranking 6th in reading and 13th in mathematics, a drastic jump in both categories.

We're doing better than that. When you break the results down by race, the US generally ranks second or first. (US whites do better than whites in Europe; US asians do better than asians in Asia, US blacks do better than blacks in the few countries with a large black population that aren't afraid to take these tests in the first place...)