Do Mars and Venus ride the school bus? Gray is part of a new crop of educators with a radical idea—that boys and girls are so biologically different they need to be separated into single-sex classes and taught in different ways. In the last five years, brain researchers using sophisticated MRI and PET technology have gathered new information about the ways male and female brains develop and process information. Studies show that girls, for instance, have more active frontal lobes, stronger connections between brain hemispheres and "language centers" that mature earlier than their male counterparts. Critics of gender-based schooling charge that curricula designed to exploit such differences reinforce the most narrow cultural stereotypes. But proponents say that unless neurological, hormonal and cognitive differences between boys and girls are incorporated in the classroom, boys are at a disadvantage.

Most schools are girl-friendly, says Michael Gurian, coauthor with Kathy Stevens of a new book,"The Minds of Boys: Saving Our Sons from Falling Behind in School and Life," "because teachers, who are mostly women, teach the way they learn." Seventy percent of children diagnosed with learning disabilities are male, and the sheer number of boys who struggle in school is staggering. Eighty percent of high-school drop-outs are boys and less than 45 percent of students enrolled in college are young men. To close the educational gender gap, Gurian says, teachers need to change their techniques. They should light classrooms more brightly for boys and speak to them loudly, since research shows males don't see or hear as well as females. Because boys are more-visual learners, teachers should illustrate a story before writing it and use an overhead projector to practice reading and writing. Gurian's ideas seem to be catching on. More than 185 public schools now offer some form of single-sex education, and Gurian has trained more than 15,000 teachers through his institute in Colorado Springs.

To some experts, Gurian's approach is not only wrong but dangerous. Some say his curriculum is part of a long history of pseudoscience aimed at denying equal opportunities in education. For much of the 19th century, educators, backed by prominent scientists, cautioned that women were neurologically unable to withstand the rigors of higher education. Others say basing new teaching methods on raw brain research is misguided. While it's true that brain scans show differences between boys and girls, says David Sadker, education professor at American University, no one is exactly sure what those differences mean. Differences between boys and girls, says Sadker, are dwarfed by brain differences within each gender. "If you want to make schools a better place," says Sadker, "you have to strive to see kids as individuals."

Natasha Craft, a fourth-grade teacher at Southern Elementary School in Somerset, Ky., knows the gender-based curriculum she began using last year isn't a cure-all. "Not all the boys and girls are going to be the same," she says, "but I feel like it gives me another set of tools to work with." And when she stands in front of a room of hard-to-reach kids, Craft says, another set of tools could come in handy.