The rules for desks and seats for children are these:
1. The height of the seat should be about two-sevenths of that of the body.
2. The width of the seat should be about one-fifth of the length of the body, or three-fourths the length of the thigh. Do not keep unfortunate little children's feet dangling all through their school years to save a few pennies on school furniture.
3. The seat should slope downward a little toward the back, be slightly concave, and have rounded edges in front.
4. There must be a back-rest.
5. The child, when sitting erect, should be able to place both forearms on the desk without raising or lowering the shoulders. This is a very important rule.
6. The seat must be correctly placed as regards the distance of its front edge from the corresponding edge of the desk.
7. The desk slope should be 15 degrees.
Badly constructed desks cause eye-strain and marked distortions of the spine. Desks should be adjustable in height, especially for growing children. School-children grow most rapidly between the ages of twelve and sixteen years—nearly two inches a year—and the desks and seats should be adjusted twice a year at the least. If a child is moved to another desk an adjustment is to be made at once.