Do your kids like to get their hands messy? Of course they do! So that is what is so great about this project—your kids can get messy, and maybe even learn something too! Fun science experiment!
Here is what you will need:
- measuring cups
- large bowl
- plastic fork or spoon
- food coloring *optional
- plastic bag (for storage and later disposal)
Mix ½ cup cornstarch with ¼ cup water. Combine until the mixture is somewhat stiff, yet gooey. You can add a bit more cornstarch or water depending on consistency. What you are looking for is a substance that acts as both a solid and a liquid.
The cornstarch and water mixture acts like a solid sometimes and a liquid at other times. This concoction is an example of a suspension – a mixture of two substances, one of which is finely divided and dispersed in the other. In the case of the cornstarch quicksand, it’s a solid dispersed in a liquid.
When you punch the cornstarch quicksand, you force the long starch molecules closer together. The impact of this force traps the water between the starch chains to form a semi-rigid structure. When the pressure is released, the cornstarch flows again.
All fluids have a property known as viscosity – the measurable thickness or resistance to flow in a fluid. Honey and ketchup are liquids that have a high resistance to flow. Water has a low viscosity. Sir Isaac Newton said that viscosity is a function of temperature. So, if you heat honey, the viscosity is less than that of cold honey. The cornstarch and water mixture and quicksand are both examples of non-Newtonian fluids because their viscosity changes when stress or a force is applied, not when heat is applied.
Solid to liquid… apply a bit of force… and back to a solid.
Very cool. Very messy. Your kids will be entertained for hours!
*Make sure to dispose of this concoction in a plastic storage bag. You DO NOT want to pour this down the drain, as it could cause a blockage.