The schoolroom should be about twenty-five feet by thirty feet with not less than a thirteen foot ceiling; this size room will be large enough for thirty pupils and no teacher should be required to take care of more than this number in a class. There should be plenty of entrance and exit doors for each room. The interior of the classroom should be attractive but plain, the surfaces smooth, the junctions of ceiling and floor with walls should be concave. All mouldings, projections, ledges where dust and dirt could lodge should be eliminated. The walls should be of such a color as to absorb as little light as possible and prove least taxing to the eyes. A light green-gray is favored. The walls must be so treated with paint or some other method employed so as to be readily washed or otherwise cleaned. White ceilings which reflect the light are best. Floors are made of hard wood in narrow planks with matched joints, or they are dovetailed. This may be laid over false floors of boards or reinforced concrete. The walls, floors, ceilings and partitions must be proof against sound, dampness, fire, vermin, and dust. Lighting The lighting of the schoolroom, the amount of glass surface or window area, will be governed by the aspect, the location of the building, direction from which the light is admitted, shape of the room and the proximity of other buildings or objects which might obstruct the light. The window area must be ample to insure sufficient light in every part of the room even on dark, overcast and cloudy days. The rule is that the window area should be at least one-fourth of the floor space and it is practically impossible to have an excessive window area for the light may be toned down and softened by shades and awnings. Prism glass is more practicable because it refracts the light and gives a more even distribution over the entire room. Most of the light should be admitted over the left shoulder of the pupil so as to eliminate annoying shadows, but it is not necessary that all the light come from the left. The windows should reach to the ceiling and the height of the sill from the floor should be about four feet. Light should never enter from the front and strike the eyes of the pupil. The upper fourth of the window furnishes one-third of the light, also the best light; therefore it can readily be seen that window shades should not be hung from the top but from the bottom, and should be rolled upward. In nature the light comes from above, hence this being natural it is consequently best. Ventilation