Learners observe a bottle containing water and oil. They are invited to pick up the bottle and mix the contents together. Because of their poor miscibility, oil and water can form “ocean waves” in a bottle. The molecules in food coloring mix well (are miscible) with polar water molecules but not with the long hydrocarbon molecules of oil, so only the water layer is colored. The oil is less dense (lighter) than water so the oil layer floats on top of the water.