Recently, I found this great article published by Montessori Foundation about why Montessori classrooms are made up of multiple age groups. This is a question often asked while touring new families so I thought it may be helpful. It reads:

Sometimes parents worry that by having younger children in the same class as older ones, one group or the other will be shortchanged. They fear that the younger children will absorb the teachers’ time and attention, or that the importance of covering the kindergarten curriculum for the five-year-olds will prevent them from giving the three- and four-year-olds the emotional support and stimulation that they need. Both concerns are misguided.

At each level, Montessori programs are designed to address the developmental characteristics normal to children in that stage.

Montessori classes are organized to encompass a two- or three-year age span, which allows younger students the stimulation of older children, who in turn benefit from serving as role models. Each child learns at her own pace and will be ready for any given lesson in her own time, not on the teacher’s schedule of lessons. In a mixed-age class, children can always find peers who are working at their current level.

Children normally stay in the same class for three years. With two-thirds of the class normally returning each year, the classroom culture tends to remain quite stable.

Working in one class for two or three years allows students to develop a strong sense of community with their classmates and teachers. The age range also allows especially gifted children the stimulation of intellectual peers, without requiring that they skip a grade or feel emotionally out of place.