Everyone who has been to a high school has seen them in full force: they're school cliques, and they can determine everything from where a student sits at lunch to how safe he or she feels walking down the hallway. But how do these social groups get started? A new study has found surprising evidence indicating that it's the school itself that determines the depth and strength of school cliques.

Think back to your own school years, and it's not hard to remember how kids self-segregated. In fact, sociologists have studied this phenomenon for years. It's common for kids to gravitate to the kids who seem most similar to themselves, whether that's because of similarities in age, race, gender, classes, sports teams or after-school clubs. But some schools have a much harder time dealing with the social network of cliques — and it turns out the schools themselves might be to blame.

Schools that offer students more choices such as different class types, course requirements, and even classroom seating are more likely to foster cliques by race, age, gender and social status. Surprisingly, the same goes for larger schools. It seems that the wider the source of a student's potential friends, the more likely students will be to segregate into tight-knit units.

On the opposite end of the spectrum, researchers found that smaller schools have fewer issues with cliques — possibly because the "cost" of excluding someone from your social network is greater when there aren't as many potential friends to choose from. In addition, schools that limit choices when it comes to interactions and classes maintain more control over social groups and often foster a system where students interact based on academics rather than social status.

The research, which was published in a recent issue of American Sociological Review, looked at friendship and social data from two different high schools at the classroom level and at the school level.

“Educators often suspect that the social world of adolescents is beyond their reach and out of their control, but that’s not really so,’’ said Daniel A. McFarland, a professor of education at Stanford Graduate School of Education and the lead author on the study. “They have leverage, because the schools are indirectly shaping conditions in these societies.”

So schools can influence the formation and strength of cliques. But should they? McFarland cautioned that the study doesn’t mean that students are necessarily better off in small schools with less choices. For one thing, this type of system tends to segregate students before they even walk through the school doors. In other words, a larger school with a more diverse student body may promote self-segregation, but a smaller, more elite school is likely to be segregated from the general population to begin with.

McFarland hopes his research can act as a springboard for future studies on the formation of school cliques and type of school environment that is best for a student's social development.

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New research finds that a school's size and policies might influence the formation of social networks.