An adult usually holds a pencil with his first three fingers,
forming a three-point grip, usually called a "tripod grasp."
This grip provides agility and flexibility for controlling
movement of the pencil.
A child, whose fine motor skills have not yet been developed,
uses a "fist grasp" with his whole hand wrapped around the
pencil. With such a grip, he can make larger movements but he
cannot make more intricate designs.
A girl can develop fine motor skills several years before a
boy, so often she can begin to write with a pencil at a
younger age than a boy.
You can give your child activities which encourage him to use
the tips of his fingers, like playing with modeling clay,
untying knots, sewing (yes, even boys can learn how to sew),
threading beads, and making baskets.
At first, you should give the child thick crayons, which are
easier for him to hold than thin crayons and pencils.
If you see that your child cannot hold the pencil with the
tips of his fingers but insists on holding it with a fist
grip, he is not yet ready.