On all musical instruments something has to vibrate in order to create sound. On a brass instrument (like a trombone) what vibrates is the brass-player’s lips. The vibrations from the lips activate the air that is in the trombone. The longer the instrument (trombone slide out) the lower the sound. The shorter the instrument (trombone slide in) the higher the sound. A balloon can also work like a brass instrument. Blow up a regular balloon and pinch/pull on the sides of the neck - you should hear a buzzing sound, similar to buzzing your lips. If you pull really hard the buzzing should get higher and vice versa. You will need: A really big balloon - about 2 feet in diameter after it is blown up Two short plastic or cardboard tubes about 1-2 feet long with one able to slide snugly inside the other. Directions: Fit the smaller tube into the neck of the balloon and blow up the balloon through the tube. You will need to pinch off the neck of the balloon between breaths - don’t get dizzy! Once the balloon is big enough, pull the neck of the balloon slightly off to one side. Hold the tube straight up with the balloon hanging down off one side. Let go the neck of the balloon. If all is right you should hear a humming sound as the neck vibrates. If all you hear is escaping air, keep trying to pull the neck further to the side and try again. When you have the humming sound, slide the smaller tube into the larger one and slowly and gently move the tube up and down - You have made the balloon trombone! Variations: you can hold the balloon under your elbow and stretch the neck of the balloon to get some sounds that are louder and more controlled, like a mutant bagpipe.