I teach Maths to 10 - 13 year old children and these resources are aimed at them! I have also written a book called, "The Aliens have landed and 174 other problems" which is available from either Amazon or The Mathematical Association. It is full of mathematical puzzles for 11 year olds upwards.
This explains how Public Key Cyphers work and includes a problem to solve. Very helpful as part of a code-breaking course. The solution is also provided. Designed for bright 13 year olds and upwards.
