Planes of Development
Dr. Maria Montessori identified four periods, which she called "planes" in a developing human. The first plane starts at birth and continues to six years; second from six to 12 years; third from 12 to 18 years; fourth from 18 to 24. All of these distinct periods have various components that need to be addressed.
First Plane, Age 0-6 years
As identified, the first plane lasts from birth to around six years of age. It is during this time that the child experiences significant physical and psychological growth. In this period the child finds himself engaged in the process of developing the psychological self and improving physical independence. Dr. Maria Montessori further explains this progress in human development with concepts such as the absorbent mind, sensitive periods, and normalization.
Second Plane, Age 6-12 years
The second plane occupies a period of time between six and 12 years of age. Psychologically, during this period children develop a predisposition to work and socialize in groups. Also, their imagination and reasoning is further advanced. Physically, at the beginning of the plane the young ones lose baby teeth and their legs and torso elongate. The rest of the period is characterized by uniform growth. In summary, the second plane is when the child fosters intellectual independence, sense of morality, and social organization. Thus, Maria Montessori created special environment, curriculum and materials to target this phase.
Third Plane, Age 12-18 years
The third period in child's development starts at around the age of 12 and continues until the age of 18. This is the time known as adolescence. During this plane, the human being undergoes physical and psychological changes particular to this stage of growth. The physical changes are in the form of puberty, and psychological alterations are characterized by creative tendencies and difficulties in concentration. Throughout this phase, Montessori observed the push for evaluation of self-worth. She believed that in the third plane, the child is the creation of adult self in the society.
Fourth Plane, Age 18-24 years
This plane of development lasts from around 18 years of age to approximately 24 years of age. Dr. Maria Montessori did not focus her studies on this period, as she believed that the child will be prepared to face adulthood having experienced the teachings of the method in the earlier stages of life. According to her, young adults should be ready to encompass the culture and the sciences and to set leadership examples. For this phase, she highlighted the importance of economic freedom in a form of work for income. Additionally, she expressed the need to continue the study of culture throughout the human being's life, rather than have it be limited by the number of years at a university.