ISEN-ASTC-L is a service of the Association of Science-Technology Centers Incorporated, a worldwide network of science museums and related institutions. ***************************************************************************** Hi Natasha, The simplest would be what I call the Jurassic Park seismograph. If you recall, each time before the T. rex appears, they show a cup or pool of water so you could see the vibration. A bowl of water with a bright lamp reflecting off the surface will show ripples when students stomp their feet, bounce a basketball, etc. It also registers trains and, large trucks driving by. You don't get a record of the vibrations, but it does get across the idea. It also shows quite a few vibrations that we usually don't notice. Robert Krampf Robert Krampf's Science Education Company www.krampf.com Sign up for my FREE Experiment of the Week e-mail list by sending an e-mail to: [log in to unmask] *********************************************************************** More information about the Informal Science Education Network and the Association of Science-Technology Centers may be found at http://www.astc.org. To remove your e-mail address from the ISEN-ASTC-L list, send the message SIGNOFF ISEN-ASTC-L in the BODY of a message to [log in to unmask]