Really? Wow, did't know that one. In the UK they're called hashes on phones and everywhere else too.
Maybee you could put next to it: (NB. UK- hash sign).
Edit: Just browsing through and you might want to put a waitkey in before end for the Chapter 3 example program so they get a chance to see the varibles printed on the screen before the program exits
.
It's also severely lacking in some areas eg. you will also need to explain about different sorts of loops instead of just Do-loops and include information the exit command. You also need to explain types too.
For Fathers and Sons who enjoy wholy spirits.