186 THE MONTESSORI METHOD
the finger of the child and to draw it very, very lightly over the surface.
Another particular of the technique is to teach the child to hold his eyes closed while he touches, encouraging him to do this by telling him that he will be able to feel the differences better, and so leading him to distinguish, without the help of sight, the change of contact. He will quickly learn, and will show that he enjoys the exercise. Often after the introduction of such exercises, it is a common thing to have a child come to you, and, closing his eyes, touch with great delicacy the palm of your hand or the cloth of your dress, especially any silken or velvet trimmings. They do verily exercise the tactile sense. They enjoy keenly touching any soft pleasant surface, and become exceedingly keen in discriminating between the differences in the sandpaper cards.
The Didactic Material consists of: a — a rectangular wooden board divided into two equal rectangles, one covered with very smooth paper, or having the wood polished until a smooth surface is obtained; the other covered with sandpaper, b — a tablet like the preceding covered with alternating strips of smooth paper and sandpaper.
I also make use of a collection of paper slips, varying through many grades from smooth, fine cardboard to coarsest sandpaper. The stuffs described elsewhere are also used in these lessons.
As to the Thermic Sense, I use a set of little metal bowls, which are filled with water at different degrees of temperature. These I try to measure with a thermometer, so that there may be two containing water of the same temperature.