What You Did
You saw the movement of cold water molecules and hot water molecules with the help of food dye. You observed that warmer molecules move faster than colder molecules.
When you added the food coloring to the different temperatures of water, the blue coloring in the cold water should have moved around more slowly than the red coloring in the hot water.
If your hot water and cold water aren’t hot or cold enough, the effect will be reduced in either direction. The greater the temperature difference, the greater the effect will be observed.The blue coloring will move faster if it ends up in the hot water instead of the cold water.
Try using ice water or, with a parent’s help, near-boiling water.