In this activity, learners will explore how the human brain interprets environmental stimuli. Learners use two point discrimination on the skin to determine the relative number of nerve endings located in the skin. By calculating the reciprocal of these measurements, learners will have the appropriate data for predicting the relative size and drawing the homunculus found on the cerebral cortex. Comparisons can be made among the homunculi of other mammals. This lesson plan includes background information, focus questions, and guide for learners.