Pencils.
They have some graphite, also known as lead, in the middle and it is
surrounded by wood, so that you can write with it without getting graphite
all over your fingers. Chalk. The stuff teachers use on the blackboard.
When you use it, you get chalk all over your hands.....chalk dust
everywhere. Why don't they cover the chalk with wood or some other
material so that no one has to get chalk all over their fingers?