This is sounds so neat!! Place 2 to 3 drops of food coloring at the bottom of each party cup and let dry. Just before serving the drinks, fill each cup with ice to hide the food coloring. While each child watches, pour the drink over the ice, and the clear water or soda will “magically” turn into a color as it fills their cup! Use different colors of food coloring so that the kids won’t know what color to expect from their “magic” soda.