Magic Mud - Cornflour Slime

One of my favourite activities is making cornflour slime, or, as some people call it, magic mud. It's super simple, educational, and most importantly fun! However, be prepared to get messy.

All you need is:

• Cornflour
• Water
• Mixing bowl
• Mixing spoon
• Food colouring

Now, what to do:

1. Start by pouring the cornflour into the bowl.
2. Now stir in small amounts of water until you have a thick paste.
3. Add as much food colouring as you like, but be warned, you will end up with coloured hands if you go crazy with it.
4. Try stirring the mixture slowly. No to hard, huh?
5. Now try it fast. This should be like trying to stir a solid; pretty near impossible.
6. If you're game, try punching the slime hand and fast. It's like punching a wall.

Check out this YouTube video to see it in action:

So what's happening?

Well, when pressure is applied the viscosity of the slime increases and vice versa. This is called a shear-thickening fluid. The opposite happens to shear-thinning fluids like blood, paint, ink and nail polish. They get runnier when you stir them. The interactions between atoms in shear-thickening and shear-thinning fluids is so complex that no one really understands what is happening, except that it's pretty cool.

Hopefully this activity and its mystery can get you or your children engaged and interested in some science!

It does keep in the fridge for several days, but you might need to give it a stir to make it work properly again.