The basic five senses that we were all taught are visual (seeing), auditory (hearing), olfactory (smelling), gustatory (tasting), and tactile (touching). Most of the Montessori sensorial activities revolve around these senses. Everything humans do involves using one or more senses. It is through the senses that infants discover the world. Without one's senses, the brain would be a prisoner to the skull. Humans experience these sensations through interactions with the environment; interpreting the meaning of these sensations for actions is called sensory processing. When a child uses her senses to discover a new object, she creates a neuronal pathway in the brain. The more often she stimulates her senses from her environment, the more likely she is to create new neuronal pathways and strengthen old neuronal pathways in the brain. Sensory development begins during gestation and continues throughout childhood.
The vision and hearing senses are the first to be developed in children. To improve these senses the parents and guardians should ensure the child is exposed to different colors, shapes, and sounds. You can hang different vividly colored and shaped chimes over the child's cradle that have a visual appeal and a soft rhythmic sound that will help develop the child's vision and auditory senses.
Maria Montessori expanded upon the visual sense, by adding a subdivision for the chromatic sense. This is being able to distinguish between colors and their gradations. She developed several color boxes to practice color recognition and grading. The baric sense is used to distinguish between different weights. The baric tablets are pieces of wood of differing weights that children balance on their fingers to compare. The thermal sense is another offshoot of the tactile sense, where children use their skin to distinguish between hot and cold. Thermic bottles can be prepared by a teacher for matching by holding one in each hand. Thermic tablets are made of different materials, such as stone, glass, wood, cork, etc., and checked by holding one on each cheek. The stereognostic sense is also known as the tactile-muscular sense. It is used to enhance the connection between the visual and tactile senses. To truly understand the curve of a circle, or the angles of a polygon, the child must trace a three-dimensional form. This technique is used throughout many of the sensorial lessons, including identifying objects hidden within a bag, simply by touching them.
“The first of the child’s organs to begin functioning are his senses....instruments by which we lay hold impressions, and these, in the child’s case, have to become “incarnated”, made part of his personality.” The Absorbent Mind, Chapter 8, p. 84
The development of the Stereognostic sense is an important part of the child's work in the Sensorial area. Just as important as any of the other of senses, the stereognostic sense allows the child to discriminate size and shape through the use of touch. Dr. Montessori wrote “When the hand and arm are moved about an object, an impression of movement is added to that touch. Such an impression is attributed to a special, sixth sense, which is called a muscular sense, and which permits many impressions to be stored in a “muscular memory”, which recalls movements that have been made." (The Discovery of the Child) The use of the stereognostic sense allows the child to have a mental picture through the use of touch and movement. Other activities that develop the use of the stereognostic sense include the mystery bag and stereognostic bag.
Sensory Disorders in Children
If a child overreacts to loud noises, avoids certain textures, appears overly uncoordinated, or simply seems to lack self-control. He or she may be experiencing some kind of sensory disorder. Of course, all children usually undergo a variety of sensory issues while exploring and interacting within their environments....