Too many exceptions to the rule

From Elizabeth Weil of the Times.

One reason for this, Giedd says, is that when it comes to education, gender is a pretty crude tool for sorting minds. Giedd puts the research on brain differences in perspective by using the analogy of height. “On both the brain imaging and the psychological testing, the biggest differences we see between boys and girls are about one standard deviation. Height differences between boys and girls are two standard deviations.” Giedd suggests a thought experiment: Imagine trying to assign a population of students to the boys’ and girls’ locker rooms based solely on height. As boys tend to be taller than girls, one would assign the tallest 50 percent of the students to the boys’ locker room and the shortest 50 percent of the students to the girls’ locker room. What would happen? While you’d end up with a better-than-random sort, the results would be abysmal, with unacceptably large percentages of students in the wrong place. Giedd suggests the same is true when educators use gender alone to assign educational experiences for kids. Yes, you’ll get more students who favor cooperative learning in the girls’ room, and more students who enjoy competitive learning in the boys’, but you won’t do very well. Says Giedd, “There are just too many exceptions to the rule.”

I think Jay Giedd, quoted above, summarizes the reasons so many policies don’t work.  “Too many exceptions to the rule.”