Set up the light station, with a single sharp light beam traversing a flat white viewing sheet.  Placing various bottles in the beam can affect the path that the light follows.  For this page you will need two flat sided plastic bottles and two glass vials, all found in your kit.  Do each of the following investigations.

1. Fill one flat sided plastic bottle with water, and alternately place it and the similar empty bottle standing upright in the light beam. Study what happens as you turn the each bottle, so that the light beam encounters it from different directions. It may be hard to see the beam while it is in the bottle, but we can deduce what happened by comparing where the beam enters and leaves as we view it on the paper.  Note that in addition to the beam that goes through the bottle, there are beams that result from reflections from the surfaces -- generally, these are dimmer and can be ignored easily, but under certain conditions they can be quite bright.
2. Lay the water-filled bottle on one of its flat sides, in the light beam. Now the bottle behaves a bit like a prism, and the beam is deflected to a different direction. Slowly turn the bottle, and observe how the final direction of the beam varies. Also notice what happens when the beam is coming out almost parallel to a surface. (There are also reflections. The situation is even more confusing than before).  How does the empty bottle behave when used in this way?
3. Fill one glass vial with water, and study what happens when you place it so that the light beam hits it on axis, or a little to one side or the other. Predict what would happen if the vial were standing in a beam that was exactly the width of the vial (and then try it, of course!).  Does the empty vial have the same effect on the light beam?