I’m rather enjoying Peter Gray’s Free to Learn… consider some of what he writes on the segregation of children according to age in school:
“Age segregation and lack of opportunities for free play add to the forces that work against the development of cooperation, compassion, and nurturance at school. Under normal conditions, children develop their abilities to cooperate and help one another in free, self-directed, social play, where they learn to resolve their differences and take into account one another’s needs in order to keep the game going. Age-mixed play is especially valuable in this regard. Reserachers have found that the presence of younger children naturally activates the nurturing instincts of older children. Older children help younger ones when they play together, and in that way they learn to lead and nurture and develop a concept of themselves as mature and caring. But little of this can occur at school, where children are forced to associate only with others of their own age and where free, unsupervised play is arare or absent. It should come as no surprise that over the past few decades – as schooling has occupied ever-larger portions of children’s lives and age-mixed play has declined – psychologists have documented a constantly rising prevalence of narcissism (defined as excessive self-concern and lack of concern for others) among young people.
The age-segregated, competitive atmosphere of school, along with students’ lack of any real voice in school governance, provides the ideal conditions for the generation of competitive coalitions, or cliques, which provide a foundation for bullying. Children who are not accepted into any of the prevailing cliques may be picked on mercilessly, and they have no way of escape.” (pp.76-77 Peter Gray Free to Learn)
“By segregating children by age, by caging them in so they can’t avoid those who harass them, by indoctrinating them in a setting where competition and winning – being better than others – are the highest values, and by denying them any meaningful voice in school governance, we establish the breeding grounds for bullying.” (p.79 Peter Gray Free to Learn)
Ref: Peter Gray (c2013) Free to Learn Why unleashing the instinct to play will make our children happier, more self-reliant, and better students for life. Basic Books: New York