A tale of three discoveries: a discovered attack proved the winning move in all three games.
Unmasked threats - discovered attacks and discovered checks - are the
most difficult threats to spot. You pay attention to the piece that
moves, but the threat comes from the piece behind.
I've attached a discovered attack training page - get your eye in! In 2010, the Devon U14 team lost an awful lot of points (or a lot of awful points) to discovered attacks, and the puzzles are all things that they missed.
Visiting the hospital recently I spotted a nice new game. You'll know the game Solitaire, where you reduce a set of pegs by capturing to a single survivor.(Peg Solitaire to the Yanks [what they call Solitaire, played with cards, we call Patience]).
ThinkFun have produced a chess version, available as a physical set, or a mobile phone app that you can try for free.