Traditionally, mixed-age classes are like a big family, and children of different ages are like brothers and sisters. However, in sibling organizations, the role of children is fixed, that is, brothers and sisters are always brothers and sisters, and brothers and sisters are always brothers and sisters. If you are a brother or sister, you have always been in the position of taking care of others, better than others; Those who are brothers and sisters are always in a position of being cared for, taken care of and disadvantaged.

The mixed-age education in Germany believes that a child's role in the mixed-age class is dynamic and will constantly change and develop: from being taken care of at the beginning to taking care of others, from being "weak" to learning "strong" and becoming "strong". With the growth of age and physical development, their psychological and social roles are constantly developing and changing. Mixed-age education provides favorable conditions for children's development and change, promotes children's socialization process, and makes children's body and mind develop synchronously. To some extent, it also avoids the shortcomings that are easy to appear in the only child.