The motor is provided with a speed control. 

Higher speeds give more extensive movements of the spheres. 

Kinetic Theory Model provides in analogue form a visual representation of molecular movement in gases.

A piston, in a wide perspex tube, is vibrated by a low-voltage electric motor housed in a box supporting the tube. 

Metal spheres, simulating gas molecules, are propelled upwards in a tube by the piston's vibrations.  

For demonstrations to larger groups illumination from the side and a black background are recommended, to highlight the spheres.

The movements of the spheres are seen to be random both in direction and extent.