1.  Refraction happens when a wave changes its speed and direction, this happens when the              wave enters a different medium.        2.  Diagram to show the path of light from air to glass to air: See Summary.        3.  a) When light enters glass from air, it bends towards the normal.                  This is because light slows down in glass as it is more dense than air.                         b) When light enters air from glass, it bends away from the normal.                  This is because light speeds up in air as it is less dense than glass.             c) Water waves travel faster in deep water but slower in shallow water.