[jgrahamc]

Rear Admiral Grace Hopper (one of the most important pioneers in our field, whose achievements include creating the first compiler) used to illustrate this point by giving each of her students a piece of wire 11.8 inches long, the maximum distance that electricity can travel in one nanosecond.

I made download and print versions of this: http://blog.jgc.org/2012/10/a-downloadable-nanosecond.html