If you want children to become responsible young adults they must have opportunities to practice both personal and social responsibility at a young age. A mixed age group allows children of different ages and abilities to help each other and thus learn responsibility. In a mixed age class it is not always the teacher who solves problems. In fact more often it is not. Instead it is another student. This is not possible in a class with students all of the same age and abilities.
Since no two students grow and mature in exactly the same way the materials available to the students are varied and numerous. The proper activity for the right moment is there to be introduced to the student when he is ready or when chosen by him as his interests dictate. Thus, no student is held back if his skills indicate a need to move on, nor is a student pressured to keep pace with skills he is not yet ready to master. The sensitive periods of each student can be capitalized upon in a multi-age classroom.