Ds is year 4, and has learnt a lot Math himself up to all year 8 topics. However the prep school Math teacher suggested that he should stop learning these "mechanics" as he can do all these Math topics well already, he should be doing more "puzzle" type of Math. The teacher recommended nrich but commented nrich is difficult to navigate at the beginning. DS looked at the website quickly, it does seems to be confusing. Anyone has any ideas on how/where to start? Thanks.