Children in the Primary Level are in grades 1-3 and are generally 6-9 years old.

Once a child turns six years of age, Montessori says that the child enters a second stage of development. Physically there are tremendous changes. The biggest difference, however, between a preschool child and the elementary child is that the elementary child explores his environment and seeks to understand the world around him by using his mind. While the young child understands and learns through his senses, the child in the second stage of development combines memory, imagination and reason instead of sensorial impressions to learn. Montessori would say that the greatest gift is the use of imagination to achieve abstraction.  

Now the questions become "How does it work?" and "Why?" instead of "What?" 

The child in the elementary classroom is involved in building relationships with peers and adults. The 6-9 year-old child becomes engaged in the construction of a community. During this period, there is great social adaptation as opposed to the physical adaptation of the preschool child. Sensitivity to belonging to the group also leads the child toward a system of justice and helps the child to develop a sense of conscience.