We educate students in groups. In addition to the obvious financial savings over individualized instruction, it makes sense for a social species to provide many opportunities for young people to interact with each other. Our K-12 school system thus provides 12,000 hours of non-kin social awareness and interaction that’s embedded within the curriculum and classroom life.

Grouping students into class groups poses the problem of who should constitute a class. Students could be grouped by various criteria, but age currently dominates. Students thus begin Kindergarten at about five, and continue through the grades with students approximately their own age.

Students who are significantly more or less intellectually advanced than the age norm create problems, so separate gifted and special education classes exist. Students who create serious behavior problems are also often placed into special classes.

A shift towards broad inclusion has occurred in recent years, partially spurred by a national policy to encourage the racial and ethnic integration of schools. The rationale is that it’s important for students in our very diverse society to become comfortable with social and cultural diversity. They thus should have daily access to as wide a range of the student population as possible. For example, placing a blind or wheelchair-bound student into a traditional classroom may create problems (just as racial integration initially created problems), but it’s important for minority and handicapped students and the rest of the class to daily confront and solve such problems. The belief is that a more accepting adult society will emerge from such inclusive efforts.

The cognitive neurosciences are now providing us with a much better sense of the organization and development of our brain, and this has led some to suggest that we should use this information to rethink how students are grouped into classes. Leonard Sax, a physician and psychologist, is active in the group who believe that boys and girls of the same age should be taught in separate classrooms. He’s laid out his case in a controversial, thoughtprovoking book, Why Gender Matters: What Parents and Teachers Need to Know about the Emerging Science of Sex Differences (2005).

What we know is that (1) males and females are structurally and behaviorally much more similar than different, (2) differences that exist don’t imply that one cognitive property or strategy is necessarily better than another, and (3) measurable differences must be interpreted in light of the within/between factor in normative research studies that compare group scores on human properties, capabilities, and behaviors. The range of scores within each group is greater than the difference between the mean scores of the two groups. For example, consider height differences in large normally-distributed male and female groups. The difference between the tallest and shortest person in each gender group will be greater than the difference between the average heights of the two groups of males and females. Thus, some females will be taller than some males in normative groups, even though the total population of males averages 7% taller than females.

Group differences thus only show group tendencies; they don’t predict for any single person in either group. So although it’s possible and appropriate to report general observations about male/female differences, it’s inappropriate to stereotype—to use a general observation about a group to predict the properties, capabilities, and behavior of any individual male or female within the group.

Given these factors, Sax argues that significant innate differences exist in the organization and operation of male and female brains, and that many boys and girls suffer because of instructional and management procedures that are better suited to the other sex.

Why Gender Matters explains and discusses the relevant research in several such key areas. For example, males and females experience auditory, visual, and olfactory information differently, differ in the sequential development of several brain systems, and tend to interact with others differently in games and work assignments.

These and other differences that Sax reports and discusses don’t imply that males are naturally more competitive and better at math and science, for example, or that females are more emotional and collaborative. Rather, Sax argues that males and females typically approach such issues differently, and are equally successful if school procedures encourage them to follow their cognitive capabilities and learning predispositions. Dual-sex classrooms typically don’t do this.

Eighty percent of the teachers in U.S. public schools are female. Sax argues that the teacher’s predispositions and interests bias curricular, instructional, and management practices, and that this bias negatively affects more male than female students—but that dual-sex classroom instruction and management also negatively affect female students.

During recent decades our society has begun to move beyond the cultural bias against female doctors and male nurses and many other formerly rigid occupational biases. Stay-at-home dads aren’t the rarity they once were. The U.S. Secretary of State is black and female. Sax sees such cultural change as very positive, but is concerned that it has seemingly stalled and that the current educational climate tends to reinforce gender stereotypes. For example, fewer women are pursuing computer science careers and fewer men arts careers than 20 years ago. Sax believes that educators need to become aware of and respond to genuine gender differences, something he feels can best occur in single-sex classrooms.

The National Association for Single Sex Public Education has succeeded in establishing experimental single-sex classrooms in various school districts. The association is working with educators to develop effective practices for gender-specific education.

Critics argue in opposition: Males and females must learn how to live together, and dual-gender classrooms provide the best possible extended laboratory for that. If curricular and/or classroom management practices negatively affect male and/or female maturation, change the practices. Single-sex classrooms are merely an extension of single-race classrooms. Single-sex schools and classrooms were historically common, but they’ve disappeared in recent years for a variety of valid reasons. Sax suggests that such criticism is mistaken.

The single-sex classroom movement is one of the first legitimate policy issues to emerge out of cognitive neuroscience research, and so educational leaders ought to understand it and thoughtfully consider all elements of the issue. Checking out the NASSPE Web site and reading Leonard Sax’s thought provoking book is a good beginning.