– There’s China and there’s China. The province of Shanghai is the wealthiest in the country. Macau province is the same China, but it scores average on math and below average on reading.
– Race is a factor (as always). In the 2006 survey, the U.S. scored really badly in science (21st out of 30 OECD countries), and back then that was almost entirely due to Hispanic students, who scored almost as badly as their peers south of the border. Just whites would’ve been 7th out of 30.