Video Demo: Fish Tank Spectrum

 
When studying light, students need to learn that visible light can be refracted into its different wavelengths.  Of course it's ROYGBIV (red, orange, yellow, green, blue, indigo, and violet).  A simple prism is usually used to do this, but I think there is a better way.  Fill up a fish tank with water, put it in the sun, use a mirror and ta da a spectrum!  Check out the video.