Materials Required
  • Four empty glasses
  • Salt
  • Blue , Black and Red ink
  • Cold water
  • Hot water
  • Test tube or any thin transparent bottle.

How to do it

  • Label the 4 glasses as hot water, cold water, hot salt water, cold salt water.
  • Add few s of blue ink in one glass, few s of black ink in another and few s of red ink in the third. Leave one glass as it is.
  • Add salt in two glasses where salt is mentioned on the label. Stir well so that the salt dissolves fully.
  • Add cold and hot water as per the label on the glass.
  • Take the test tube or thin bottle and slowly pour the cold salt water into the test tube till it fills to 1/4.
  • Slowly pour same quantity of cold water into it.
  • Slowly pour same quantity of the hot salt water into it.
  • Slowly pour same quantity of hot water into it.
  • Ask the child to observe what happens. It should form 4 different layers.
  • As the density is variant, the 4 layers are formed. Also because of the colours, child could see the different layers.

Explanation

The density of the water varies when the salt is added and the density varies when there is different in temperatures.