Crayon box illustration to communicate the diversity of the world.

If you use a 64 crayon box and say each crayon equals 100 million people, you get a world with 6.4 billion. (I believe that number is a a little low... but it's close.) Then you can take out the red, white, and blue crayons to illustrate Americans (roughly 300 million people). Look at the numbers and diversity that is left.