Code breaking for kids

Since Mom is teaching math these days, I thought you all might be interesteed in this:

http://home.egge.net/~savory//blog_feb_08.htm#20080207
http://home.egge.net/~savory//blog_mar_08.htm#20080310

P.S. I stumbled across this while looking for a picture of a tin-foil hat. No telling what you will find on the internet.