Today, we tried to make a goo with strange behaviour. This is a very simple experiment. You only need water, cornflour, bowl, plate and spoon.
The children put cornflour onto the disposable plastic plate and added water. After a quick stir with the spoon, they added more water until the goo was thick and creamy. They could then pick up the goo to roll it between the fingers.
When they rolled the goo, it felt dry and hard. When they stopped rolling, it slowly spreads over their fingers. Both of them were amazed with the consistency. Kept them entertained for quite a while by rolling it over and over again.
The reason for that is cornflour particles float in water. When you roll the flour and water, the particles are forced together. When you stop rolling, the cornflour and water separate again. The goo behaves like quicksand.
Both children had a hard time understanding the reasons behind it but it gave them a lot of fun. They played for at least 10 good minutes with their goo!