Imagine you are watching a four-year-old boy carry a wooden box with a red lid to a table. Then, he goes back to the shelf of Sensorial Materials and brings over a matching box—this one with a blue lid. (These are called the Sound Cylinders. Each is filled with about one ounce of grains of sand ranging from very fine to coarse, in subtle gradations so that each cylinder makes slightly different sounds when shaken).