The National Centre for Excellence in the Teaching of Mathematics is probably the best website you can possibly find to support you as a parent or practitioner when it comes to teaching or supporting Mathematics.
They have materials for every age group, all linked to the National and Early Years Curriculum. They have fantastic articles, exemplary lessons to watch and all the teaching materials you could need to teach every incremental step of mathematical knowledge your child requires.
Why not have a look? https://www.ncetm.org.uk/