Alan Turing Cryptography Competition

"The Alan Turing Cryptography Competition is aimed at secondary school
children in the UK up to Year 11 (England and Wales), S4 (Scotland), Year
12 (Northern Ireland). You don't need to be a computer whizz or a
mathematical genius — you just need to keep your wits about you and be
good at solving problems!"

Although based around ciphers and cryptography, the competition presents
the questions as puzzles and may be of interest to some here. It has just
started, so Chapter 1 is available now.

https://www.maths.manchester.ac.uk/cryptography/

--
David Entwistle