School Desks
The furniture most important to the health of the child is the desk and the desk chair. These should be very carefully adjusted to the child; if this is not properly done the child will have a tendency to assume a faulty posture which will favor the development of curvatures of the spine and other physical defects.
The height of the desk should be such that the pupil will not find it necessary to raise the shoulder in placing the arm on the desk to write, or so low that he will have to bend forward. The top should slope at an angle of about fifteen degrees. The best distance from the eyes is from twelve to fourteen inches.
The height of the chair from the floor should be very carefully adjusted to the student and it should allow the feet to rest comfortably on the floor; that is, when the student is seated the thighs should be level and the leg at right angles to the thigh, thus allowing the feet to rest on the floor. If the chair is too low there will be too much weight thrown on the back of the thighs while a chair that is too high produces too much flexion of the lumbar region of the spine. The slope of the seat should be slightly backward and downward and the depth about two-thirds the length of the thighs. The back of the chair should slope slightly backward and should be made to fit the curve of the back.
The chair should be placed far enough from the desk so that the abdomen will not touch its edge. When properly adjusted in most cases the edge of the chair will project under the edge of the desk about one inch. In the lower grades it is best to adjust the seats and desks to the child twice a year.
Blackboards
The best material for blackboards is slate, which furnishes a surface that is not shiny and will not reflect the light. They can be washed and easily kept clean and thus lessen the nuisance of dust. Blackboards should never be placed between windows. When possible there should be no windows on the same wall because when pupils are looking at the board there should be no light shining in their eyes. The blackboards are best placed opposite the principal light.
Dustless chalk is best and the use of colored crayons made of arsenic or sulphide of mercury should be prohibited, since the dust from these crayons is poisonous.
The blackboards should be plainly visible to all the pupils and care should be taken that all writing or other work on the board is large enough for the pupils to see without eye strain. The distance of each pupil from the board should be governed by the strength of vision.