RECENT STORIES about whether men and women think and learn differently because their brains are different have argued that any cognitive differences that may exist are small and that classrooms should not be divided by gender.
I agree with the view that teaching math in different ways to girls and boys is pernicious and silly. But schooling is about teaching socially productive citizenship as well as geometry, and the difference in male and female propensities toward self-destructive violence is no myth.
Men are more than eight times as likely as women to commit murder and more than 50 times as likely to engage in a gang-related killing. My gender commits 84 percent of all violent crimes. Young men are four times more likely than women to carry a gun and five times more likely to commit suicide.
The tendency of young men to be violent is not peculiarly American. A classic criminology textbook, "Principles of Criminology," notes that crime rates for men greatly exceed those for women "for all nations, for all communities within a nation, for all age groups, for all periods of history for which reliable statistics are available, and for all types of crime except those peculiar to females."
Recent research on suicide bombers by my colleague Effi Benmelech finds that more than 94 percent are men. Male violence is not even uniquely human. Richard Wrangham's superb book, "Demonic Males," is about murder among apes.
While male violence is universal, societies differ in their ability to channel that violence. With the right kinds of investment, male aggression can be put to good uses, such as winning the World Series and running hedge funds.
We are failing our young men because we have not made that investment. We have made our streets safer by incarcerating millions, more than 90 percent of whom are male, but we have inflicted a terrible cost on millions of lost boys.
Investing more in schools that provide both economic opportunity and social skills is an alternative to prisons in the fight against youth violence. But should those schools refuse to "sort students" on the basis of gender or should they recognize and react to the greater male propensity toward crime. There is no single, right answer and pragmatism, not doctrine, should shape our policies.
Sometimes, we should refuse to recognize gender and treat men and women identically. In other settings, it may make sense to use gender-specific tools to help violent young men and even to separate boys and girls. We shouldn't require teachers to communicate in the same way to girls and boys if more specialized messages can help build better connections with both genders.
Programs like Big Brothers Big Sisters, which has helped thousands of young people, have long used gender as a sorting mechanism. A big brother may find it easier to connect with an at-risk boy and that connection may end up saving the boy from self-destruction. Indeed, its website proclaims "though Big Brothers Big Sisters is always looking for volunteers from all walks of life, right now there is a greater need for men."
Single-sex schools are among the thorniest issues relating to gender and at-risk youth, and the evidence on such schools is murky. Many single-sex schools have been successful, but their success may tell us more about the children they admit than about the impact of the school.
Still, the magnitude of society's problems compels us to be open to educational innovation. While co-education is surely best for most Americans, we should also allow parents the opportunity to enroll their children in single-sex charter schools that give more discipline for boys, more safety for girls, and more targeted support for both genders. We should not rule out a single-sex program like Baltimore's Baraka School, which gave at-risk boys the chance to live and study on the Kenyan outback.
I want my daughter and son to be taught science and math in exactly the same way, but I will not be surprised if my son needs a little more help learning to control his teenage aggression. After all, I needed a little more help.
Edward L. Glaeser, a professor of economics at Harvard University, is director of the Rappaport Institute for Greater Boston.