After a few days studying how patterns can be used to communicate information (Top Secret and Binary Code), its time for them to get to the heart of the standard, choosing the best system to send a message, and being able to explain why.
I have them begin by doing some research using Comparing Codes. Late in the year, after many lessons on finding quality resources online, my students could do this on their own, but this certainly could be completed as class. The Comparing Codes Key has some possible answers, though there are certainly others.
The last question requires students to come up with a coding system using a new sense. I really was looking for a way to push students into something not derived from Morse Code. If they can come up with a smell based code, I think that would fit the bill!