The line of people (molecules) forms an elastic solid by linking arms.

S- waves in a solid.  Note that the motion of each person (molecule) is perpendicular to the direction that the wave travels. (MPEG Video)

The line of people (molecules) forms a liquid by unlinking their arms.

A P-wave travels easily within an liquid.  It would also have traveled in a solid, but I don't have a video of it doing so. (MPEG Video)

Note that an S-wave will not travel in a liquid. (MPEG Video)

These videos were taken at the IRIS Consortium Earthquakes Workshop for College Faculty held on October 24, 1999, during the Geological Society of America's annual meeting in Denver, CO. 

Professor Larry Braile of Purdue University is at the end of the line causing all of the waves.  Check out his web site for some additional great ideas for earthquake education.

The class also tested their building-design skills with Larry's shake table.

A too flexible building doesn't do so well! (MPEG Video)

A more rigid winner! (MPEG Video)