This week the Year 7 Science club looked at the property of viscosity by making oobleck. 

Oobleck, named after the green slime in a Dr Seuss book, is a Non-Newtonion fluid, which means that it does not have a constant viscosity.

Squeezing oobleck causes it to become hard like a solid, but when you hold it gently in the palm of your hand, it becomes a runny fluid.  Oobleck is easy to make (two parts corn starch to one part water) and great fun to play with.