Originally Posted by phey
doing less structured math - reading through math books (Murderous Maths, Number Devil, Life of Fred, code books...are there others?)

- "Great Source" math books, e. g.:
http://www.amazon.com/Great-Source-Math-Know-Mathematics/dp/0669535966
- AOPS Beast academy (only grade 3 is available)
http://www.artofproblemsolving.com/Store/beastacademy.php