The OECD scores of American blacks and Hispanics, bad as they are, were better than those of their counterparts in majority black and Hispanic countries.
Think about what that means. Every race that comes to America does better here than in countries where their race dominates with the sole exception of Asians who are the top performers wherever they are.
On the other hand, there's a fixed spread among races, with blacks and Hispanics as a group ALWAYS on the bottom, never on top.
In other words, it's not the education system only, nor even culture (though that's certainly a contributing factor), but the race that counts.
No one is allowed to talk about it. All research on the subject has been squelched, and even prominent scientists like Watson of DNA fame were demonized for their findings that race matters in performance.