Cornstarch and Water
Materials: ★☆☆ Easy to get from supermarket or hardware store
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★☆☆ Minimal safety procedures required
Categories: Fluids and Surface Tension, Kitchen Chemistry, Particles and States of Matter
Alternative titles: Oobleck, Non-Newtonian Fluid Demonstration
Summary
This experiment uses cornstarch and water to create "oobleck," a non-Newtonian fluid that behaves like a liquid when poured but like a solid when struck or squeezed. It provides a hands-on way to explore suspensions and unusual fluid dynamics.
Procedure
- Pour cornstarch into a large bowl. First explore its dry texture by feeling it with your hands.
- Mix water slowly into the cornstarch, about ½ cup of water per cup of cornstarch. Add food coloring to the water first if desired.
- Stir and knead the mixture thoroughly with your hands until it flows slowly when at rest but can be rolled into a ball when squeezed.
- Experiment with the mixture: press it quickly, punch it, let it drip through your fingers, or place objects on it to see how it behaves.
- When finished, dispose of the oobleck in the trash, not the sink.
Links
The science of cornstarch and water - Massachusetts Institute of Technology (MIT):
Cornstarch Walk on Water - Cool Science Experiment - Sick Science!:
📄 Oobleck – The Cornstarch And Water Experiment - Science Bob: https://sciencebob.com/oobleck-the-corn-starch-and-water-experiment/#google_vignette
Variations
- Make a larger batch and try walking across it quickly in a shallow container.
- Test the effects of adding more or less water to adjust its thickness.
- Compare oobleck with other household non-Newtonian fluids like ketchup or slime.
Safety Precautions
- Oobleck is safe to touch, but avoid eating it.
- Food coloring may stain skin, clothing, or surfaces—use protective coverings.
- Do not pour oobleck down the drain; it can clog pipes. Dispose of it in the trash or mix into soil.
Questions to Consider
- Why is oobleck called a non-Newtonian fluid? (Because its viscosity changes depending on the amount of pressure applied, unlike Newtonian fluids which have constant flow rates.)
- What happens to the cornstarch grains under pressure? (They lock together, resisting movement, making the mixture behave like a solid.)
- Why does oobleck eventually settle if left alone? (The cornstarch particles are suspended, not dissolved, so they sink over time.)
- What real-world materials or situations act like non-Newtonian fluids? (Examples include quicksand, wet sand, ketchup, and some industrial fluids.)