Different liquids have different densities , which means that some liquids are heavier than others.
You will also learn how detergents work to get greasy, dirty clothes clean. In a glass jar, pour one cup of water and a thin layer of cooking oil. Screw on the top and shake the bottle to mix the oil and water. The two liquids always separate into two layers, no matter how hard or long you shake the bottle. The oil is less dense, or lighter, than the water so it floats on top.