Science talk With Chris Duggan House of Science

Have you ever read Dr. Seuss's book Bartholomew and the Oobleck?

It's a story about a gooey greeny blue substance called an Oobleck that fell from the sky and wreaked havoc in the kingdom, and it is now up to an ordinary boy named Bartholomew Cubbins to work alongside the Oobleck to save the kingdom from destruction.

With this fun and easy science experiment, you can make your own Oobleck. It is a messy activity but at nothing like the potential destruction in the book, the only mess here will be your hands as you play with your Oobleck.

Equipment:

· Small bowl

· Cup/drinking glass

· Fork

· Tablespoon

· Cornflour/corn starch

· Food colouring

Instructions: 1) Add one tablespoon of cornflour to your small bowl.

2) Fill the cup with water.

3) Now slowly add water from the cup to the bowl of cornstarch. Add one tablespoon of water at a time, stirring with the fork after each spoonful of water. Make sure to break up any clumps that have formed.

5) Keep adding water, one spoonful at a time. Observe what happens when you add more water.

6) Once you have added five tablespoons of water, observe the mixture in your bowl – how does it look? How has it changed?

7) Continue adding water, but now add half a tablespoon at a time, mixing after each addition.

8) Stop adding the water when the mixture looks like it has turned into Oobleck, or the cornflour has flowed together like a liquid. It will take six to eight spoons of water in total. How many spoonful's did it take for you? How would you describe how the Oobleck looks?

9) Add a few drops of food colouring to your Oobleck and stir with the fork. If the mixture still seems chalky white, add a bit more water.

10) You can now play around with your Oobleck. Try stirring it fast and slow, picking it up, squeezing it, making it into a ball, allowing it to flow through your fingers, hitting it with the spoon… How does it move? What does it feel like?

NB– when you are done with the Oobleck, dispose of it in the rubbish bin. Do not pour the Oobleck down the drain, it can easily clog pipes.

The Science Behind:

The Oobleck you made in this experiment is called a non-Newtonian fluid. This means that it does not act like most ordinary fluids like, water, juice, or washing liquid, when you interact with it.

When most liquids are pushed against, like how you poked the Oobleck with your finger or fork, they move out of the way. The harder they get pushed, the faster the liquids move out of the way.

Oobleck does not behave like this. When you put stress on it, such as pressing down or poking it with the fork, it becomes harder and changes the liquid to a solid.

When you don't put pressure on it e.g., if you hold it in your hand – the Oobleck changes to a runny liquid.

Other Exploration: Starches are often used to make gels. What happens if you heat up the Oobleck? How does it change? What new things can you observe?