Who doesn't like to dive in into the science of sound by creating a fun musical instrument your children could play with? To create a sound, you need to create a vibration. In this experiment, when you blow the air, you make the column of air inside the bottom part of the straw to vibrate. But when you submerge the straw into water, you reduce the volume of vibrating air, and that affects the pitch of sound waves. It could be noisy but remember you are doing it for science.