Children learn at their own rate, with no fear of retention. In same-grade classrooms, children are retained if they do not master content by the end of the year. In mixed-age classrooms, children have more time to master content, and this removes their fear of being retained in school. Children develop a sense of family with their classmates. Older children have the opportunity to serve as mentors and to take leadership roles.
Children are more likely to cooperate than compete.
The spirit of cooperation and caring makes it possible for children to help each other as individuals, not see each other as competitors. Older children model more sophisticated approaches to problem solving, and younger children are able to accomplish tasks they could not do without the assistance of older children. This dynamic increases the older child's level of independence and competence. Children are invited to take charge of their learning, by making choices at centers and with project work. Children have almost an extra month of teaching time, because the teacher does not have to spend the early weeks in the school year getting to know each child.