Cornstarch Quicksand from Martha Stewart’s website

With Martha Stewart’s demonstration:
http://www.marthastewart.com/page.jh...catID=18&site=

With written instructons:
http://www.marthastewart.com/page.jh...KIDS&site=kids

This cornstarch quicksand is an easy way to teach your kids about hydrosol, a compound in which a solid is scattered throughout a liquid. In a bowl combine 1 cup cornstarch with a 1/2 cup of water; stir with your fingers until it forms a thick paste. Punch the surface. Your fist will barely make a dent; when the compound is mixed, the process traps tiny drops of water between tiny bits of starch making the surface feel solid. Now slowly dip your hand into the paste. Pick it up and it will ooze through your fingers. Squeeze it, turning it over and over in your hands; watch how it goes from goopy liquid to dry powder and back to glop—when there is no pressure the mixture turns watery again.