Then the couples will be increased to four or five, and little children of three years old end by pairing of their own accord ten or a dozen couples of mixed tablets.
When the child has given his eye sufficient practise in recognizing the identity of the pairs of colors, he is offered the shades of one color only, and he exercises himself in the perception of the slightest differences of shade in every color. Take, for example, the blue series. There are eight tablets in graduated shades. The teacher places them one beside another, beginning with the darkest, with the sole object of making the child understand "what is to be done."
She then leaves him alone to the interesting attempts which he spontaneously makes. It often happens that the child makes a mistake. If he has understood the idea and makes a mistake, it is a sign that _he has not yet reached the stage_ of perceiving the differences between the graduations of one color. It is practise which perfects in the child that capacity for distinguishing the fine differences, and so we leave him alone to his attempts!
There are two suggestions that we can make to help him. The first is that he should always select the darkest color from the pile. This suggestion greatly facilitates his choice by giving it a constant direction.
Secondly, we can lead him to observe from time to time any two colors that stand next to each other in order to compare them directly and apart from the others. In this way the child does not place a tablet without a particular and careful comparison with its neighbor.
Finally, the child himself will love to mix the sixty-four colors and then to arrange them in eight rows of pretty shades of color with really surprising skill. In this exercise also the child's hand is educated to perform fine and delicate movements and his mind is afforded special training in attention. He must not take hold of the tablets anyhow, he must avoid touching the colored silk, and must handle the tablets instead by the pieces of wood at the top and bottom. To arrange the tablets next to one another in a straight line at exactly the same level, so that the series looks like a beautiful shaded ribbon, is an act which demands a manual skill only obtained after considerable practise.