Water
Ice cube tray
Blue and red food colouring
2 cups
Large container
1. Add blue food coloring to tap water and pour the coloured water in an ice cube tray. Leave the tray in the freezer for at least 3 hours or overnight to make coloured ice cubes. Alternatively, you can just chill the water in the fridge without making ice but make sure the blue water is much colder than room temperature.
2. Pour warm water (you can heat the water on a stovetop or microwave) into a cup. Add red food colouring and mix.
3. Take out the blue ice cubes and place them in a separate cup.
4. Fill the large container with room temperature water.
5. Pour the blue ice cubes into one end of the tank.
6. Pour the red warm water into the other end of the tank.
7. Watch and see what happens