Here is a fun exercise which may be useful when coaching kids and/or beginners. You start with an empty chess board, and each player has a rook in their hand. The first player places a rook on any empty square, then the second player does the same. Then each player moves their rook as normal, with one important restriction. You cannot move you rook across the path of the other rook. The winner is the first player to run the other player out of moves.
Two questions quickly arise. Is it a guaranteed win for one or the other player? And what is the winning strategy?