3. sensory systems: include the major features involved in vision and hearing, along with how each functions so that we can see and hear.

A normal human being has five basic sensory systems - sense of sight, smell, taste, hearing and feeling. Sight is made for looking using the eyes. Smell of determining odors using the nose. Taste is for tasting foods using tongue. Hearing is knowing decibels using the ears. And feeling is using the skin.