Light travels in straight lines, except when it
      doesn't. Having seen a shadow cast by some solid object, rectilinear
      propagation (read: definition of a straight line path) seems
      logical. But the behavior of light becomes the focus of some
      attention when we observe those instances when it is forced out
      of a straight line path. We engage two of these phenomena, reflection
      and refraction, every day. Knowledge of these optical phenomena
      will cause you to understand how light behaves in your every
      day coming and going. For example, we see most of the objects
      around us because light leaves some source, reflects off an object,
      and enters the eye.The reflection is not random but rather is
      well understood. Light entering the eye is directed to the retina
      by a phenomenon called refraction. The retinal image is then
      coded as electrical signals sent to the brain for processing.
      What you will encounter in these lessons are text pages, web
      sites, and in-class activities that will cause you understand
      the behavior of light when it is reflected and refracted. An
      attempt has been made to separate consideration of these two
      phenomena, although some web sites readily combine them. We will
      consider these early sites as they apply to reflection and revisit
      them when we encounter refraction.