The most potent motivation is the desire to write, and this is closely allied with the understanding of the usefulness of being able to write and the value of the written symbols, words and figures. Good handwriting is influenced by posture which does not strain the eyes or lead to unnecessary fatigue. Motivation to write will obviously grow naturally out of the child's pleasure in drawing and painting, but also will be dependent upon the availability of the necessary materials and the experience of seeing other people write, and understanding why they do so. The style of script in writing should be identical wherever possible with the type the children will meet elsewhere in school. Dysgraphia is similarly incapacitating—the child being unable to make lines and shapes he wishes. It is difficult for a teacher to decide quickly whether mistakes made by children are the normal ones which time and practice will cure.