ABSTRACT
Children of three years already know how to count as far as two or three when they enter the authors' schools. They therefore very easily learn numeration, which consists in counting objects. The making of change is a form of numeration so attractive as to hold the attention of the child. It is most interesting to study the expressions upon the faces of those who possess zero. The didactic material which the authors use for the teaching of the first arithmetical operations is the same already used for numeration; that is, the rods graduated as to length which, arranged on the scale of the metre, contain the first idea of the decimal system. The necessary didactic material consists of a number of square cards upon which the figure ten is printed in large type, and of other rectangular cards, half the size of the square, and containing the single numbers from one to nine.
