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When I was a kid my mom showed me how much fun it was to play around with corn starch and water.  When you get the mixture right you get this liquid that is not quite a liquid.  When you press your finger into it quickly it seems to turn into a chalky solid. When you leave it alone it will drip and ooze just like a liquid.  I did not know this at the time, but this is what is called a non-Newtonian fluid.Watch more non-Newtonian fluids in action.
 Thanks to Jennifer Ouellette and George Johnson at BloggingHeads.tv for the link.