In a mixing bowl, add 2 parts cornstarch and 1 part water. For example, you could use 1 cup of cornstarch and ½ cup of water.
Mix the cornstarch and water together until they are well combined. The mixture will be thick and difficult to stir.
If you want to add color to your oobleck, you can mix in a few drops of food coloring at this point.
Once the mixture is well combined, you can start playing with your oobleck! You can pick it up and shape it with your hands, or let it drip through your fingers. Oobleck has a unique texture that is both solid and liquid at the same time. It will become more solid if you squeeze it or hit it with force, but it will become more liquid if you let it rest.
Once you are done playing with the oobleck, pour it into your mini pie pan. Bury treasure in the mixture. Allow the mixture to dry at room temperature for several days. Once mixture is completely dry, have kids use hammers, brushes, picks and other utensils to pick apart and find the treasure inside the pan.
Video
Notes
Never pour oobleck down drains. Dispose in a garbage can.