DIY Amazing Density Tower from Things Found in Your Kitchen by stevespanglerscience: Make objects float in the middle of a liquid with this amazing trick. The idea is cool, but you need a tall glass (a vase?) and lots of each liquid to make it look good.
Inventing a machine is a fun science activity for kids. This bouncy ball machine invented by 4 year old Aiden combines two simple machines, a lever and an inclined plane, to release bouncy balls on the ground.