Density and temperature

On Monday in class we did the density and temperature demonstration,  basically we had two cups, one hot one and one cold one (also had dye).  Then we filled the cups on eachother, with the cold one facing down and hot one still up. Then the red and blue dye conjoined and made this nasty green color,  but when we did it the other way with the hot water cup upside down and the cold one right side up then the blue and red water were perfectly separated.  This is because warm water rises and when It was at the bottom it mixed with the cold water.  The reason being is because although each cup had the same energy, cold water is more dense than warm and sinks to the bottom.  This is why when you are in a pool the farther you go the colder your feet get, because the cold water is at the bottom.