The Ice cube experiment

Here is some information about what we did in class today.  Freeze some ice cubes that you have coloured with some food dye.You need to use room temperature or warm water. Put the ice cube in and watch the cold water that is coloured fall down to the bottom. This water is colder and therefore denser. As that water reaches the same temperature as the rest it will move upwards as more cold goes down.

Another idea as shown in this video it to see the difference between fresh water and salty water.
 Have fun.