One aspect of a Montessori classroom is that there is a 3 year age span among the children. A Primary Montessori Classroom is designed for the 3-6 years old children.
Maria Montessori found this to be most beneficial for children and now, educational research supports this practice, although it’s typically only found in Montessori schools.How often now does the child have the experience of living in the family with several brothers and sisters? Not quite that often. So he is not receiving the full social experience. Perfect social environments for the child are children with the age difference year or two.

And Montessori classroom is a big family with a lot of children of different age, but not that different to be impossible to study together. This difference helps to avoid many conflicts that are present in the same age groups. In Montessori groups, children have natural age hierarchy, and the older Child tends to help, to patronize and to teach little one. Little kids know that they can always get help from older ones.