The Sensorial area of the Montessori classroom is easily identified by its bright and colorful materials. The materials in this area are the most standardized of all the Montessori materials and are consistent in appearance across settings. For example, in virtually any Montessori pre-primary classroom, you would find a Pink Tower that would look just like the Pink Tower in every other Montessori classroom.
The Montessori Sensorial materials, however, are unique in that most traditional preschool settings do not have materials quite like them. While any developmentally appropriate preschool would provide children with a wide variety of sensory experiences, most do not have materials designed specifically to isolate single perceptual qualities. Each activity in the Montessori curriculum consists of a set of objects which, when grouped together, represent a single perceptual quality such as "color" or "sound." This is possible because each object in the set is identical in every way except that one quality. For example, the Pink Tower cubes are identical EXCEPT for their size. Whereas many classrooms may have blocks of differing sizes that can be stacked to make a tower, Maria Montessori took the idea one step further by making all the cubes the SAME COLOR. This way, the child can focus more easily on what ONE attribute makes the cubes different. If the cubes were multi-colored, the child could be distracted by all the "red ones" together and all the "blue ones" together, etc. To me, this is an ingenious way to really help a child focus on what is intended by the material.
I think it is fitting here to point out why children in Montessori classrooms are taught to carry the Sensorial materials from the shelf to the rug one at a time. It is not because the teacher is trying to be overly controlling or rigid. Instead, it is to help the child gain maximum perceptual understanding from the material. A good example is the Red Rods. When presented with this material, the child is encouraged to carry each rod from the shelf to the rug one at a time and with one hand on each end of the rod. By doing this, the child can fully experience the LENGTH differences between the shortest red rod (which is 1 decimeter in length) and the longest one (which is 1 meter in length). It is fun to watch a little one try to stretch their arms wide enough to carry the longest red rod. (And to see the resulting smile on their face). If the child had carried several rods in their arms simultaneously, they would miss out on this valuable sensory experience.
Think of it this way: Imagine that your child is using crayons for the first time. Instead of coloring by holding the crayon vertically, they are trying to color with it by moving it horizontally across the paper (I am assuming the crayons still have the paper on them). Yes, they are still having the experience of exploring with crayons. However, that experience is somewhat limited by the way they are using the materials. It is likely, then, that as a parent, you would gently redirect them towards a more productive and beneficial way to use the crayons.
Why are the Sensorial materials so important? Why are they included in the Montessori classroom? Following is a quote from Maria Montessori herself which sheds some light on these questions.
"In order to develop his mind a child must have objects in his environment which he can hear and see. Since he must develop himself through his movements, through the work of his hands, he has need of objects with which he can work that provide motivation for his activity."
Obviously, all learning occurs through the senses. Young children (and, of course, babies) are constantly using their senses to interact with and make sense of their environments. How wonderful it is for them to have such beautifully and thoughtfully designed materials to support this sensory exploration.
Finally, the Sensorial materials are also designed to indirectly prepare children for work in other curricular areas. For example, many of the Sensorial materials contain ten pieces which prepares children for the decimal system. The left-to-right, top-to-bottom order of most Sensorial presentations prepares the child for directionality in reading and writing. And, the teacher's modeling of the prehensile (tripod) grip and the pencil-sized materials (such as the Knobbed Cylinder Blocks) prepare the child's fingers for gripping a pencil.
I will leave you with a few photos from my Sensorial shelves.
Just out of the edge of the photo you can see the Pink Tower on the left. The Red Rods are on the top shelf. Middle shelf has from L to R: Brown Stair, extension cards using Pink Tower and Brown Stair, Sound Cylinders. Bottom shelf L to R: Color Box 1, Color Box 2, Color Box 3, Color Book activity (see photos below), and the card pouch with color sorting picture cards.
Here is the Color Book activity as it is on the shelf. The 11 colored pencils (corresponding to the 11 colors in Color Box 2) are in a little wooden tray I found when thrifting. The little baskets holds blank books with my example book on top.
To do this work, the child takes a blank book and the colored pencils and uses one color per page to color the blank color tablet.