I have been tasked to give a set number of presentations to prepare to become an instructor. My first was a 10 minute presentation on Divorce (Uncontested Divorce in Texas). Then, a 20 minute presentation on Superman. Recently, I did a 30 minute presentation on Radio Wave Propagation.
Unfortunately, my next presentation, 50 minutes, looks like it will be on Cryptography. I don't know this subject as intimately as the last two, but I believe I can get 50 minutes out of it, especially covering a lot of the earlier and middle history of the art, and possibly getting into explaining some of the more primitive means of encoding information.
Whee. I have less than 24 hours to get the Powerpoint together...