Thought this was interesting. In countries with gender equality (Sweden, Norway and Iceland are examples) girls do just as well as boys on standardized math tests. In Turkey, not such a gender-equal society, the average difference is 23 points. Researchers examined the test scores of 276,000 children in 40 countries, found that this pattern held around the world. "Average girls' scores improved as equality improved and the number of girls reaching the highest levels of performance also increased." So more equality leads to ... more equality.
"The research also found a striking gender gap in reading skills. In every country girls perform better than boys in reading but in countries that treat both sexes equally, girls do even better." The global average difference is 32.7 points. In Iceland, another country noteworthy for its gender equality, girls' average scores were 61 points higher than boys.