Children need people in order to become human . . . . It is primarily through observing, playing, and working with others older and younger than himself that a child discovers both what he can do and who he can become—that he develops both his ability and his identity . . . Hence to relegate children to a world of their own is to deprive them of their humanity, and ourselves as well.
—Urie Bronfenbrenner Two Worlds of Childhood: U.S. and U.S.S.R. (1973)