Refraction:
Refraction is the bending of a wave when it obliquely enters a new substance where it travels at a different speed.

1. In the right frame you see a PhET simulation.  Double click on “More Tools”.  Now you see a light source (it looks like a silver cylinder with a red button).  The light source is in the top part of the frame which is air.  The bottom of the frame (which is a darker color) is supposed to be glass.
2. Click the red button on the light. You see a beam of light strike the glass.  Note that a small amount of light is reflected, but the majority of the light goes into the glass (where it travels more slowly). You also see the dotted line which represents the normal, perpendicular to the glass surface.
3. In the lower left corner, click the “Angles” box so you can measure the angles more accurately than you could by using the protractor.
4. Now notice that you can drag the light, varying the angle of incidence.
5. Perform whatever experiment has been assigned by your teacher.