Prepare a "magic elixir" which has nearly the same index of refraction as Pyrex test tube. Pour the solution into a beaker and place one or two Pyrex test tubes in it. The test tubes are "invisible" from a distance. One might tell the class that the liquid has a memory. That is, if a test tube is broken and the pieces placed in the liquid, the atoms will separate and within seconds re-arrange themselves and reform the test tube!
|"Magic elixir" solution box with test tubes
|or corn syrup kit with glass balls