If you have a child who is interested in maths, check out: https://parallel.org.uk/ https://parallel.org.uk/ "A home for curious mathematical minds. For ages

If you have a child who is interested in maths, check out: https://parallel.org.uk/ https://parallel.org.uk/ "A home for curious mathematical minds. For ages 10-16 anywhere in the world. 100% free." I particularly recommend the weekly quiz newsletter, which explores all sorts of interesting maths, not generally covered in school.