Place a drop or two of food coloring into each section of an ice cube tray before freezing. Use different colors and stir them slightly to mix evenly. Freeze the colored water. Plan to add a colored cube or two into different colored drinks, such as lemonade, water and fruit punch. Have students predict what color the liquid will change into once the ice cubes melt. Add the ice, let them melt, record the observations and enjoy the drinks.
Fill two identical clear glasses or beakers with equal amounts of water. However, fill one with fresh water and one with salt water. Add one ice cube to each container and place a drop of food coloring in the water. Do not stir or shake the water. Compare which ice cube melts the fastest and how the food coloring flows through both the fresh and salt water. Salt affects the temperature and density of the water, as evident by the path the food coloring takes, whether the ice cube floats or sinks, and the speed at which the ice cubes melt.
Fill shallow containers with water, about 1/4-inch deep. Mix in one to two drops of red, blue or yellow to the different containers, and place an ice cube in the water. Let kids drop an extra one or two drops of food coloring -- red, blue or yellow - on top of the ice. The color should be a different color than the water. As the ice melts, the food coloring will blend into the water, creating a different color. This helps teach kids about primary colors and how they mix together to make secondary colors.