Place the large glass or plastic block into the clear plastic box as shown.  Direct a laser beam through the box and into the block at a 45 degree angle to the edge of the block.  Note that the entrance and exit beams are offset from one another.  Pour Wesson oil into the box to just above the level of the laser beam and observe that now the laser beam is now a straight line with no offset because the Wesson oil and the plastic block have the same index of refraction.

NOTE:  The following takes 1 full days notice.

The "Phantom Crystals" or "Growing Spheres" are commonly used as a substitute for soil in potted plants or as an absorbent in baby diapers.  They are able to absorb a large amount of water and keep it from evaporating, and so they are used to keep plants from drying out under stress conditions.  The crystals are a mixture of: 25% Hydroxyethel Methacrylate, methacrylic acid, acrylimide copolymer, cross-linked homopolymer for absorption and desorption of water, and 35% silica to stabilize the system.  They have the same index of refraction as water and are therefore invisible in what looks like a beaker of pure water.  Shine a laser beam through the beaker and the beam goes straight through as you would expect if the beaker contained only water.  Pour some of the water out so the crystals are exposed and you will see the laser beam being refracted by the individual expanded crystals.