Montessori defined the stages of child development (she called them planes of development) from 0 – 6, 6 -12 (and then 12 – 18 and 18 – 24). She based this on scientific studies (still valid today) that a child’s physiological development reaches a new stage at these ages. This is why Montessori primary schools start at age 6. Socially and emotionally, as well as academically, the development of a child between 5 and 6 is significant. Though many parents may feel that their children are “ready” for school, they come to realise that waiting until they are 6 allows the child to take advantage of leadership and other learning opportunities at pre school. Both academically and socially the child makes much progress between age 5 and 6 (including consolidating their early learning by sharing it with other young children) - and they settle better into primary school as a result of this.