A liquid whistle is like blowing on a straw in a glass of water, but instead of a straw, it’s a small hole in the side of a container. When air is blown into this hole, it creates a sound that’s kind of like a whistle! This happens because the air bubbles get trapped in the liquid and create vibrations. The pitch of the whistle depends on how much liquid is in the container and how much air is being blown into it. It’s a fun way to make music with water!