Complex sentence: Coleman (1961) studied the culture of adolescents in high schools in the Chicago area and concluded, among other things, that adolescents do form a society and that a psychology of learning based on students as isolated entities would be markedly incomplete.
Split into simpler sentences: Coleman (1961) studied the culture of adolescents in high schools in the Chicago area. He concluded, among other things, that adolescents do form a society, and that a psychology of learning based on students as isolated entities would be markedly incomplete.