Transmission of sound waves through different mediums is an example of an experiment for kids. This could involve playing music from a device that is held in the air, under water or behind a wall, demonstrating that sound waves can travel through gas, liquid and solid phases.
Another example of an experiment involves investigating the speed of sound. An experiment for the speed of sound is recording lightning and thunder during storms; the lightning is seen before the thunder is heard because light travels faster than sound. This experiment is an excellent demonstration of sound, as it teaches children that different waves move through matter faster than others (e.g. light is faster than sound).