This is a bit tangential but, kind of in f/u to your questions:
At our local public grade school, Asians make up 20% of our school (according to the school website). The AVERAGE STAR test result (STAR test is a yearly achievement test kids take in California) for the Asian kids out of a total of 1000 points was 980. The average for white students was 930 and for Hispanics was 870.
Alot of the Asian kids I have met at our school come from lower income families and they speak Chinese as their native language.