The PISA is a set of tests given to 15-year-olds worldwide in reading, mathematics, and science literacy. These are the tests that are often used, rightly or wrongly, to show that US students lag behind those in many other nations.
What the graphic above indicates is that among students with low socioeconomic status*—in the lowest quartile for each nation—the US has the smallest percentage of "resilient" students, meaning students who overcome their socioeconomic disadvantage to score in the top quartile on the PISA. All of the other nations listed on this graphic, and the average of nations in the OECD study, have a higher percentage of resilient students than low-achieving students from that lower quartile of socioeconomic status.
Lest you think that we simply have a higher percentage of disadvantaged kids, the study is clear that we're in fact below average in that regard. On the resilience chart above, China, Vietnam, and even Poland have a higher percentage of children in the lowest socioeconomic quartile than we do. Other countries are simply doing a better job at pushing their disadvantaged kids upward, to the point that they are more likely statistically to perform well than they are to perform poorly.
I'm not going to suggest that these studies are crap, because I'm guessing that resilience is actually some combination of all of those factors. There are lots of models out there now that use aspects of lesson relevance, classroom relationships, and student engagement to try to reduce learning gaps and draw all children into the mix. But there's something wrong with what we're doing. Are we not expecting enough of certain kids? Even with AIS, are we providing less support for them than Switzerland or Singapore does? Is there some kind of tracking going on in other countries that actually benefits disadvantaged students? Are their teachers better than ours at tamping down self-fulfilling prophecies about kids? What exactly is going on?
If I were a grad student in an ed program, this is what I'd be looking at, because I can't think of many things more useful to know.
*It's worth mentioning that OECD measures socioeconomic background a bit differently from many other studies. It includes the International Socio-Economic Index of Occupational Status (ISEI); the highest level of education of the student’s parents, converted into years of schooling; the PISA index of family wealth; the PISA index of home educational resources; and the PISA index of possessions related to “classical” culture in the family home. OECD/PISA has also done its own assessment of equity and overcoming social background. The executive summary is worth reading.