I've had a lot of fun with the students over the past 2 weeks of camp using codes. It's easy to fill a period or 2 with this. I usually see which team can solve the code the fastest, then have them write their own code and give it to another group to solve. I give points to whichever team is the quickest. Once they realise this, they try to create as long codes as they can.
The book cyphyer is really fun and simple, but my students found it confusing. Make sure they understand completely before you start. Basically you just take a book and write 3 numbers followed by a dash on a piece of paper. Page number, line number, word number- repeat. They can make any sentence 'I am happy' 'I can run' etc and find the words in the book. Then give the numbers to another team and they crack the code. Of course, the code can only be found if they use the right book, so you can give them a few different books and they have to see which sentence makes sense. Really fun.
I didn't end up using the cylinder code. Though seems you could srapo the paper around anything( a book etc).
Edit: You will need to change the code of slide 3 unless you're name also happens to be James.
