Welcome!
smile

You've received great replies already. I'll just add a few thoughts about math opportunities which may be of interest:

1) Epsilon Camp provides an opportunity to enjoy high-level math and meet like-minded peers.
2) UW Math Talent Search provides practice problem sets and solutions, which may be useful as material for a parent, mentor, or academic coach to review with a highly interested student.
3) Moscow Puzzles is a popular math puzzle book.