On average, across more than 60 countries, that difference between the richest and poorest is the equivalent to three years of schooling by the age of 15.
Only about one in 10 children from poor backgrounds will achieve the same results at those from wealthy backgrounds. The children of more prosperous families are travelling in an educational fast lane, with more support from home, a higher chance of getting into a good school and university, and benefiting from the interventions of better-educated parents. The accumulation of advantages will amplify differences.
According to the study, on average by the age of 15 about 13% of the variation in students’ performance will be determined by their social background.
This varies between countries. In the UK, it’s below average at 11%, with Norway and Estonia lower at 8%. In France it’s 20% and in Germany and Switzerland it’s 16%.
In countries such as Singapore, Japan and Finland, the test results of the poorest 20% are higher than the richest 20% in the Slovak Republic, Uruguay, Brazil and Bulgaria.
The UK does quite well on this measure, with the median point for UK students being above the wealthiest 20% in Italy and not far behind those similarly advantaged students in Spain.