Regarding the sex difference at 4th grade, many islam-dominated countries show no significant difference, whereas nearly all "western" countries show girls doing worse. Perhaps a data point in favor of sex-segregated education? Or a side-effect of different rates of attendance at the sorts of educational institutions surveyed?
Interesting observation. Does it indicate that the more subtle forms of gender oppression in western societies are more detrimental to math education outcomes for girls than explicit state sanctioned oppression?
https://timss2023.org/results/grade-4-math-achievement-gende...