Oobleck

Measure 2 cups of cornstarch and pour it into a mixing bowl.

Gradually add 1 cup of water to the cornstarch. If you wish to add color to your oobleck, mix the food coloring with the water before adding. Stir the mixture slowly until it becomes hard to mix.

If the mixture is too runny, add more cornstarch; if too thick, add more water. Adjust until you reach a consistency that feels solid when you squeeze it, but runs through your fingers when you let it sit.