Walk into a Montessori Early Childhood classroom anywhere in the world and you are likely to spot a set of materials unique to Montessori but common among Montessori classrooms. The Sensorial lessons, hands-on, didactic, elegant manipulatives that build and refine children's sensitivity to the physical world, are some of the most recognized Montessori materials. But why do we spend so much time focused on the children's senses?
If you're a student of philosophy, you may have come across the Peripatetic axiom, "Nihil est in intellectu quod non sit prius in sensu," Thomas Aquinas' observation that there is "nothing in the mind that was not first in the senses." Aquinas' writing adapted Aristotle's earlier proposal of the intellectus agens, or "active mind,." While Aristotle was arguing for the ability to derive universal meanings from empirical data, and Aquinas was arguing for the discernment of the divine through the experience of the senses, Montessori's application argues that learning about the world comes through experiences in that world, and that the specific development of the First Plane, from birth through age six, requires isolated experiences with quintessential examples of particular concepts. In other words, for the child to understand the concept of "blue," they must have hands-on experiences that isolate the quality "blue." For the child to understand the concept of "sweet," they must have hands-on experiences that isolate the quality, "sweet."
The intent, then, of the Sensorial materials is to meet this developmental need for isolated experiences with all the different ways in which the child might describe their world. While the world in its entirety would be overwhelming to the child, the child nonetheless is driven to make sense of all that stimulation, to name and experience and classify all the different impressions the world is making on their intellect. The Sensorial materials are designed to support the child in naming, classifying and discriminating between the stimuli of the senses: visual, auditory, tactile, gustatory, and olfactory.
The lessons for visual discrimination vary from differences in color and shade to differences in dimension, length, width and size. When you see children engaging with the Pink Tower or the Color Tablets, when they are able to scan the Red Rods to know which one is next or match items from around their classroom to the subtle distinctions in the green palette, they are refining their visual discrimination. The lessons for tactile discrimination exploit the child's natural tactile sensitivity. You might notice your child isolating subtle differences in degrees of roughness on the Touch Tablets, or exploring the related stereognostic sense (the relationship of touch and muscles) by sorting the shapes of all the puzzle pieces of the countries of Europe in a Mystery Bag. The lessons for auditory discrimination include nuanced differences like those between the course and rough sand in the Sound Cylinders, to a reinforcement of the western scales represented in the Montessori Bells. Lessons for the gustatory sense isolate distinct tastes, allowing children to compare salty to bitter, bitter to sweet, and so on. Even the child's sense of smell is supported through special materials that allow them to classify and compare common scents they may encounter.
Because the child is intrinsically motivated to make sense of the world around them, these materials enchant them. To an outside observer, both the structure and the skills of each lesson may seem simple: unadorned wooden cylinders filled with sand or wooden blocks to stack and unstack. To the child, however, these are the keys to understanding the world, the qualities they need to name, define and master the concrete world around them. In each self-correcting, didactic material, the child explores, develops and ultimately masters a single isolated concept. Together, they can use these concepts to discriminate between the sounds they'll need to know to read words aloud or the shapes they'll need to know to tell the difference between a 6 and a 9. They'll be able to create more nuanced artwork and to transcribe music. In short, they'll be able to influence in real, authentic ways the world around them, by first securing their ability to notice and name the distinct qualities within it.