Students are not to break the skin or cause any injury. Take the precaution to direct students to follow your instructions carefully. Ask students to list the various sensations they feel at different sites. Ask them to explain how the point of the pencil could feel different. There are different types of nerve receptors in the skin.
Some receptors detect pressure.
Others detect heat, cold and pain. At another site the point feels much sharper but not cold. Most high school books include a cross section diagram of skin. Students will notice that in some areas of the skin, there is much space between the receptors. In other areas, such as skin over the lips, the receptors are bunched close together.