<p>My onw theory about why girls outperform guys: the big switch in most of the country in the past 30 years from junior high schools to middle schools. </p>
<p>It hurts because boys, in general, get their academic sea legs a bit later than girls do, mature slower, start to take their studies seriously a little later, etc. So by the time kids move to HS, more girls than boys will be on the fast academic track. If a guy gets his act together in 10th grade, while the girl did it in ninth, it is very difficult in many systems for the boy to move to the faster paced academic track. Not only did the guy start HS behind, but he will be left behind–as many parents who have tried to get their late-blooming boys into stronger classes will testify. Thirty years ago, however, HS began in the 10th grade more often, and guys had that extra year to get their s**t together. </p>
<p>Same principle holds true, I believe, in moving from elementary school at grade 5 to middle school vs moving from elementary school at grade 6 to JHS. Girls often read sooner and learn to “do school” a little faster, so that they enter MS already ahead of the slower-developing boys. </p>
<p>I’ve never seen any evidence to prove or disprove. Just my theory about why girls are doing so much better over the last 30 years or so. The time frame for switching educational levels favors those (more often girls) with advantages that keep getting compounded the longer they are in school</p>