Oobleck

Oobleck has very unusual properties that can fascinate scientists for hours. Here's how you make it:

Pour 1 1/2 cups of cold water into a large bowl and add 4 drops of food coloring. (Any color) Mix it thoroughly until the water is a uniform color. Add one box of corn starch (16 oz) and let it sit for about 10 minutes. Slowly mix it by hand to get out all the lumps and dry spots. You have Oobleck!

You will find that this substance behaves like a liquid when it sits, but becomes a solid under pressure. Try squeezing a handful and then open your hand. It's very cool stuff!