Tutoring talented year 7 need hard maths questions for that age

Hi, I'm currently tutoring a 12 year old boy who is very talented for his age (scored highly in the UK Junior Maths Challenge I believe, don't know what National Curriculum level he is though).

I'm looking for some questions of varying difficulty to try with him (going from comfortable to a bit of a stretch), particularly in the areas of nth term, loci and probability but other areas would also be good.

I've been looking at GCSE questions as well as maths challenge style questions, anywhere else I could look?

Thanks