What you need
About 5 kg of cornflour
A large bowl
Find a place where it’s OK to get messy. Mix some of the cornflour and water together into a thick paste. Keep mixing until it’s ankle-deep.
Jump very suddenly onto the mixture. Try jumping on and off, or standing still.
Results & explanation
You shouldn’t sink if you jump suddenly, but if you stand on it, you’ll gradually sink.
The mixture is a special type of liquid that gets less runny when you stir it and turns solid if you hit it hard. The force of the impact makes the starch in the cornflour clump together so it supports your weight at first.
PS – Marvin & Milo are (c) IOP and can be freely used in schools. Please do get in touch if you’d like to modify or use them for commercial purposes.