Drum
Physical concept: Sound waves
Age Group: 0 and Up
What is it?
This toy is a drum that has a clear plastic top. Directly below the clear plastic top is a sealed plastic bag that contains a viscous, non-toxic colored liquid with glitter and small stars, etc. When a child strikes the drum the sound waves from the drum cause the liquid to move and visually demonstrate sound waves.
Inspiration
I know that children love hitting things. Since they'd already be inclined to hit objects I figured I would provide an object that is acceptable to hit. Drums are made for striking and they make lots of noise, which kids enjoy as well. The next logical thing would be to make the sound waves visible somehow to the kids, which is why I decided to include the liquid below the top.