In a previous post ("why do things freeze and melt?") we have seen that matter can be solid, liquid or a gas. Have you encountered anything in your home that does not fall easily into any of these categories? For instance, what about toothpaste?
Actually, some materials can behave both like a solid and like a liquid, depending on how we interact with them.
Today, we will do an experiment with corn starch: amazingly, you can gently submerge your hand in it, as if it was a liquid, but if you tap it, it feels hard like a solid! We call materials that behave like this "non-Newtonian".
For an explanation of what is happening here, see this cool video from MIT