The size of the school and each grade make the environment like a family. Student know each other and interact with various teachers and even the principal at a personal level.
The addition of "houses" creates a great sense of team spirit and accountability for my child. It also allows the students to interact with kids outside of his grade. My son has already made a number of good friends within a short period of time. One of the motivators to move my son from his previous Montessori school to Sunnybrook is the class size. I wanted my son to experience a more "real world" class experience, without having to be in a very large class where his needs could be forgotten. With only fifteen kids in his class, he has a good balance in learning how to work with other kids, "sharing" the space, and being able to learn from others. The overall size of the entire school is not too big or small, and creates a great sense of community.