EDUCATION OF THE SENSES 195
with the pink cubes is very attractive to little ones of less than three years, who knock it down and build it up time after time.
II. Differential Visual Perception of Form and Visual-tactile-muscular Perception
Didactic Material. Plane gRometric insets of wood: The idea of these insets goes back to Itard and was also applied by Seguin.
In the school for deficients I had made and applied these insets in the same form used by my illustrious predecessors. In these there were two large tablets of wood placed one above the other and fastened together. The lower board was left solid, while the upper one was perforated by various gRometric figures. The game consisted in placing in these openings the corresponding wooden figures which, in order that they might be easily handled, were furnished with a little brass knob.
In my school for deficients, I had multiplied the games calling for these insets, and distinguished between those used to teach colour and those used to teach form. The insets for teaching colour were all circles, those used for teaching form were all painted blue. I had great numbers of these insets made in graduations of colour and in an infinite variety of form. This material was most expensive and exceedingly cumbersome.
In many later experiments with normal children, I have, after many trials, completely excluded the plane gRometric insets as an aid to the teaching of colour, since this material offers no control of errors, the child's task being that of covering the forms before him.
I have kept the gRometric insets, but have given them a new and original aspect. The form in which they are