This is one for the inner nerd in us all when the weather closes in! It’s not just Little Explorers who will be stunned by the magical properties of this fabulous goop. You simply need cornflour, water, and food colouring.
Your Little Explorers can do this unaided and it’s great to see them experiment freely. Ask them to take a hand-sized scoop of cornflour and whack it into a large bowl- mixing bowls are perfect. Drizzle in some water and stir slowly to a thick paste, then add one teaspoon more water.
When they try to stir it will be almost completely solid and you might all think it needs more water. But here comes the magic. Before you add any more water, ask your Little Explorers to do this spooky trick. Pick up a big handful and roll it hard in your hands – for a moment, you'll have a solid and dusty dry golf ball, before it surprises you by starting to ooze through your fingers back into the bowl!
What the children will have made is a fascinating material that acts like a liquid until any pressure is applied, like pushing with a spoon, when it instantaneously, and only while pressure remains, turns to a solid. Get a big bowl of it and let it slide around, then ask them to splash it with a spoon - it will freeze solid on impact!
What our Little Explorers found really funny was trying to colour it. They poured in a few drops of food colouring then tried to stir....cue shouts of 'I need more water! It won't stir!’ They found that letting it run from side to side in the bowl was the only way to mix in the colouring.
Despite appearances, this is really very easy to clean up!
- Expert Explorers: This incredible mixture has been used to make crash gear for motorcylists, skateboarders and soliders! It is brilliant as it is totally flexible until the moment you fall, when it instantly hardens up. Cornflour goop is doesn’t follow the usual rules of fluids. When pressure is applied, its viscosity increases – this is called shear-thickening. Most fluids are shear- thinning – for example ketchup which becomes fluid when stirred. Cornflour is made of lots of tiny starch particles. Water gets in amongst them and lubricates the flow when you move it slowly. But when you whack it, the particles jam together, creating a solid structure of lumps which can’t move.