To provide a simplified chart, capable of providing an accurate and easy reference to a standard change in which deciduous teeth are replaced by permanent teeth, in general household.

Two circular rotating plates are rotatably connected with each other, and the lower circular rotational plate is concentrically divided into a plurality of lines. One of them displays the change of ages in the peripheral direction, and the other lines display the respective number of standard upper teeth, standard lower teeth, deciduous teeth and permanent teeth, and the total number of them so as to correspond to the respective ages. The simplified chart is provided with a cut part, which part is formed in the front circular rotating plate in a way that specified ages and indicated items on the respective lines, corresponding to the ages, can be seen on the front circular rotating plate during the rotation of the front circular rotating plate or the lower circular rotating plate. Thus, the standard change in the tooth replacement system is accurately easily made reference to in general household when the simplified chart is handed to parents.