Sensitive periods are characterized by observable behaviors such as an activity being irresistible for a child once he or she starts it. A passionate interest can develop and the same activity is often returned to time and again. I have noticed how three-year-olds for example love to wash their hands, whereas ten-year-olds do not.
Montessori observed 6 sensitive periods in a child's life. These sensitive periods are not consecutive; some overlap and some are continuous. These periods are described below.
During this sensitive period, there is a need for a precise and determined environment, which can be observed by the joy which children show at seeing things in their proper places (Montessori, 1966). The presence of this sensitive period however, is even more evident when the order is somehow interfered with. For example, Montessori describes the agitation of a 6 month old when an umbrella was placed unusually on a table. It was only with the removal of the object that the child became calm. In the words of Montessori the "object out of place had violently upset the little girls pattern of memory as to how objects should be arranged" (Montessori, 1966, p.50). The need for order is also displayed by the great lengths young children will go to put things back in their correct place.
2.Refinement of the senses
Montessori believed children take in information about the world through their senses. In very young children this appears as a curiosity to explore the environment with tongue and hands. Usually coinciding with crawling, the child is seen to regularly pick up objects and put them in their mouth. Children should therefore be given access to objects and activities in their environment which they can explore freely to allow this sensitive period to occur.
Language plays an important role in intellectual and cognitive growth. Right from when a child is born the baby is tuned in to language, and begins to make babbling noises as opposed to the noises of the telephone or the doorbell! It is clear that "the child must naturally hear the sounds in use among his own people before he can repeat them" (Montessori, 1988, p.106).
4.Coordination of Movement
Montessori observed that during this period, children love to go on long walks (a fact not always recognized by their parents who may place them in buggies when the child would probably much prefer to be on its feet!). At this stage, unlike an adult who walks for a purpose, the child walks for the sake of it, to perfect the skill. Montessori cites examples of children who spent over an hour "descending and ascending steep stairs with very narrow steps" (Montessori, 1966, p.78) and you often find open stairs in public places will be full of children scrambling up and down perfecting their movements.
5.Noticing Small Details
At this stage the child may become engrossed in extremely tiny objects, for instance tiny insects barely visible to the human eye. It is often common for children who are now mobile to be fixated with small objects such as ants, pebbles and grass, and they will often stop to examine such small objects when out walking.