Area of Science: Chemistry
Meant for at least Grade K-3 (age 5-7).
This experiment is edible.
An adult need not be present.
Combined in just the right proportions, a mixture of corn starch and water makes a slimy-yet-firm goo.
Corn starch, water, container, stirring rod, measuring spoon.
Tastes bland. Kind of messy, but you can wipe up the debris with a broom.
How to do the experiment:
Combine a handful of corn starch with a spoonful of water. Stir, and add more water if the substance seems too crumbly. Properly mixed, the substance should seem liquidy on top. Poke it with your finger to make sure. Now pour a little into your hand, squeeze, and release. Have fun, but if the ooblech seems to be drying out, add a little more water.
The forces of attraction between the starch molecules and the water vary with the amount of applied pressure. When are the attractive forces strongest? When are they weakest?
Non-Newtonian Fluids (MadSci Archives).
Or try running a search for Non-Newtonian, fluid on the MadSci Search Engine.
This experiment was wholly inspired and suggested by Jay Greytok at the Haverford School in Haverford, PA, USA.