Materials:
Corn starch
Water
Food coloring (optional)
Bowl

Directions:  Pour about a cup of corn starch into a bowl.  Add food coloring to your water as desired, then slowly add to the corn starch as you mix with a spoon or your hands.  The mixture will be difficult to stir -- that is the fun of Oobleck!  Add water until the mixture is solid enough to pick up but "melts" in your hands when you let go. Add more cornstarch if it is too runny, add more water if it is too stiff.  Getting it to the right consistency is half the fun!

Extensions:  Try hiding treasures in the Oobleck, like coins or small toys, and invite kids to dig them out.  Also try cutting and scooping it with various utensils.

Science:  Oobleck is a silly made-up word for this remarkably simple but interesting solution.  It acts like a solid when pressed on (like when you are stirring), but acts like a liquid when the pressure is released.  Liquids are substances that flow and take the shape of their container; solids are substances that hold their own shape.  A substance that behaves like both a liquid and a solid is called a "non-Newtonian fluid" because it defies the definition of liquids offered by Sir Isaac Newton.

Helpful Tip:  Oobleck can be challenging to clean up from surfaces. It doesn't stain -- it's just messy and smears when wet.  The best way to clean it up is to wait for it to dry, then wipe it with a dry cloth like you are cleaning up dust.