Direct students to take careful notice the sensation as they gently push the pointed end of the pencil on their skin. Move the point of the pencil one or two millimeters in any direction and push again. Make note of the sensation. At some sites within the square inch students will detect a cold feeling. At other sites the pencil point will feel hot, pointed and painful, or there will be no sensation at all.
Students can plot the sites of various sensations on graph paper.
Use different colored markers or letter designations indicated the sensation felt at various sites. It is not the intent of this activity to inflict pain. 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.