A series of compounds in small vials is brought close to the poles of a large, strong permanent magnet.
An H2O ice cube is less dense than liquid water, but a D2O ice cube is more dense than liquid water.
When a sample of sodium chloride, NaCl, is brought near the poles of a magnet, there is no attraction of the sodium chloride to the magnet.
A piezoelectric crystal is pressed and released producing an electric current that lights an attached bulb.
A piezoelectric crystal is pressed producing an electric current that lights an attached bulb. While still pressed the electric circuit is broken. Once the circuit is restored and electricity allowed to flow, the stress in the crystal is relieved.