[Illustration: (A) DRAWING TABLE AND INSET. (B) WOODEN TABLETS. These are partly covered with sandpaper to give rough and smooth surfaces. (C) SOLID INSETS. With these the child, working by himself, learns to differentiate objects according to thickness, height, and size.
[Illustration: (A) BROAD STAIR. (B) LONG STAIR. (C) TOWER. Blocks by which children are taught thickness, length, size.
But this part of education, like that of the sense of taste, can be obtained by the child during the luncheon hour;--when he can learn to recognise various odours.
As to taste, the method of touching the tongue with various solutions, bitter or acid, sweet, salty, is perfectly applicable. Children of four years readily lend themselves to such games, which serve as a reason for showing them how to rinse their mouths perfectly. The children enjoy recognising various flavours, and learn, after each test, to fill a glass with tepid water, and carefully rinse their months. In this way the exercise for the sense of taste is also an exercise in hygiene.
_I. Differential Visual Perception of Dimensions_
_First._ Solid Insets: This material consists of three solid blocks of wood each 55 centimetres long, 6 centimetres high and 8 centimetres wide. Each block contains ten wooden pieces, set into corresponding holes. These pieces are cylindrical in shape and are to be handled by means of a little wooden or brass button which is fixed in the centre of the top. The cases of cylinders are in appearance much like the cases of weights used by chemists. In the first set of the series, the cylinders are all of equal height (55 millimetres) but differ in diameter. The smallest cylinder has a diameter of 1 centimetre, and the others increase in diameter at the rate of 1/2 centimetre. In the second set, the cylinders are all of equal diameter, corresponding to half the diameter of the largest cylinder in the preceding series--(27 millimetres). The cylinders in this set differ in height, the first being merely a little disk only a centimetre high, the others increase 5 millimetres each, the tenth one being 55 millimetres high. In the third set, the cylinders differ both in height and diameter, the first being 1 centimetre high and 1 centimetre in diameter and each succeeding one increasing 1/2 centimetre in height and diameter. With these insets, the child, working by himself, learns to differentiate objects according to _thickness_, according to _height_, and according to _size_.