Montessori defined four stages of development and labelled them as the four planes of development, noting that within these stages, the development is intense at the beginning, consolidates and then tapers to the next. Key to all the planes of development is the individual’s need for independence. This is expressed differently throughout the planes. These planes of development are the basis for the three-year age groupings found in Montessori classes: ages birth to three, three to six; six to nine; nine to twelve; twelve to fifteen; and fifteen to eighteen.

• Characterised by the “Absorbent Mind” in which the child’s mind is like a sponge, absorbing all that is in the environment.
• At age Birth-3 this is unconscious. At age 3-6 this is conscious
• Characterized by “Sensitive Periods” which include the intense need for: Order, Language, Refinement of the senses, Movement
• Children of this stage are concrete thinkers
• During this stage there is the construction of the psyche
• At this stage children enjoy working alone
• Physical independence is the main desire now – “Help me to do it for myself!”
• The child wants to be free to work independently within a structured environment doing real activities with an intelligent purpose.
• The child’s natural ability appears through freedom in the prepared environment.

• Characterised by reasoning with imagination and logic.
• Intense interest in all aspects of culture so that the child can easily assimilate concepts, particularly in maths, that are usually reserved for secondary school and beyond.
• They have a sensitive period for social order and relationships and they enjoy working in groups
• Are uniquely sensitive to moral justice and fairness
• “Cosmic Education” – the child wants to know about the whole and his/her place within it and can appreciate the interconnectedness of all things and people.
• It is at this point they thirst for the Five Great lessons – the Story of the Universe, the Story of Life, the Story of People, the Story of Numbers, and the Story of Communication
• Intellectual and moral independence are desired now: “I can work on my own and I know what’s right.”
• 6-12 is known as the “bridge” to abstraction – or the transition from concrete to abstract thinking
• Preference to work in groups
• Intellectual independence is the main desire now – “I can “think it” myself”.

• Characterised by self-concern and self-assessment.
• At this stage adolescents are involved in critical thinking and re-evaluation and experimentation.
• This is a transition period both physically and mentally.
• The young adult is beginning to try to find a place in this world, sensitive period for exploring the world on their own
• Characterised by construction of social and moral values, extreme social sentiment
• “ErdKinder” or “Children of the Land” – Montessori envisaged the child practising for life in society by working together in a live-in community where some kind of economic activity is managed by the children themselves.
• Cultural development which has been ongoing is solidified in this plane.
  Emotional Independence from adults – “I can stand on my own”.