[jplusequalt]

>who are more amenable to sitting quietly and paying attention

Is this explanation not making a blatant assumption here that girls are statistically less hyperactive and distracted than boys?

[rocmcd]

"Hyperactive and distracted" is not necessarily the exact reason, but there is a large, well documented gap in performance for boys vs girls in elementary school (at least in the US).

[rootusrootus]

Is that controversial (assuming otherwise normal children, excluding anybody with ADHD, etc)?