[Reily]

” ...America’s performance was worst in math, scoring an average of just 470 — a full 20 points below the OECD average. High performers in math included Singapore (564) and Hong Kong (548), but also Japan (532), Switzerland (521), and Germany (506)....”

You have to watch statistics like this and take them with a grain of salt when comparing to American educational performance. All of the countries named in that above quote are demographically very homogeneous when compared to the USA. I would like to see the USA scores broken out demographically before I get to upset about them.

[NobleFree]

Averages can be very misleading. The relevant question is how many American students performed at a high level; the average is very possibly dragged down by a low-score bulge, which could very well exist for the reasons you suggested.