Flame tests are useful to identify the presence of particular metal ions in solution.

The flame tests above show (a) strontium, (b) sodium, (c) lead, and (d) potassium. This is the basis of colors in fireworks. Consider using the link to the right and clicking on the Anatomy of a Firework and On Fire (Hot Science) Links.

I know that it is small, but here is a cartoon relevant to our recent study of light. Contributed by Julia D.