[throwerofstone]

I am not waving away all other factors, I am merely stating that the difference of mental development between girls and boys is, at least to me, quite obviously the largest by far. Mental development has an enormous impact on school performance. Areas that "our" Western school system bases its grading on, from memorization to attention, are things that children only get better at when they grow more mature.

The lack of quality in modern school systems aside, I do not believe in forced equality and fully believe that sorting children by age hurts their academic progress tremendously. By extend, separating boys from girls while teaching each at a different pace might actually improve the educational quality of every child, rather than trying to appeal to merely the average for whatever reason. I believe that the above applies to any characteristic. Education should, in my opinion, be based on an individual's learning capability, but I suppose that would go against everything the modern school system stands for.

[DiggyJohnson]

I don’t think that your answer is obvious at all. It seems just as or much more likely to do with differential factors other than age (pedagogy, environment, etc.) than it is model boys as being N-2 years “behind” the girls. That seems very narrow.