More on Schooling

Senior makes compelling points about the high school environment itself. While the neurological and psychological causes of adolescence are prominent factors in why the high school experience is so lasting, the school system itself also contributes to it. As we have discussed some of the flaws of the school system and its repression of students' individuality, the school environment itself can be harmful.
 One of the most interesting points is the age divisions. School is traditionally broken up into grades by age divisions and in some uncommon cases, students are able to stay back a year if needed. Maturity ranges widely and just because some has reached a certain age doesn't mean they are suited for the academic and social aspects of high school. As Senior says, high schoolers are grouped by the general category of age but seldom are similar or have much in common.
This age division also separates students from adults. The high school biosphere creates a certain type of homogeneity, distinct from the outside world. Most students are isolated from adults in a social setting and grow up in a school system largely unable to communicate with anyone other than their peers. Abolishing of child labor laws enforced school have helped to foster a generation gap.
From a sociological standpoint, it's also an interesting concept that high school is a box like any other. That is, it is a microcosm, a community, which like any other social group, degenerates into certain parts. High school is more noted for the cliques, aggression, and drama because of hormonal and neurological processes at this time in an adolescent's life. High school breaks down into primeval  displays of superiority and power. Generally, popularity is gauged on basic things such as material possessions, physical strengths, attractiveness and the ways of perception dictate the social pattern.
As in any other microcosm, that which is different is seen as a threat. So nerds and weirdos get filtered to the side. As the article points out, this is common in high school however, similar principles apply outside of this bubble, but these people just find separate niches.
Overall, the school system itself and inevitable traits of human nature contribute to the formative high school experience.