[Ciexyz]

This is distressing news.

[WL-law]

This is NOT distressing news -- the story says nothing more than that when MEAN SCORES of all students collectively in a population are measured and pooled, either across states or across countries, then the countries with the highest number of minorities will rank lower, as the minority students draw down the mean.

It says NOTHING about the number of high achievers, or the qualities of the highest achievers.

In stories such as this one, the information supporting my point is always obliquely (or usually not-at-all) presented: here it is in buried late in the WashPost story:

A more detailed comparison of U.S. students' performance in math with the achievements of students in 24 other countries over more than a decade will be released early next week.
.....
Jack Jennings, director of the Center on Education Policy, cautioned that the PISA survey measures application of basic math concepts in real life rather than scholastic achievement or theoretical skills such as calculus and algebra. He also noted that the United States is a much more diverse country than most of its competitors, with a significant proportion of minorities, who traditionally score lower on standardized tests.

So there you have it.

And, if you follow the links to the actual web site of the testing organization, only then can you confirm that, yes, the stats presented are MEAN SCORES for the entire student population.