While children play games a point to keep in mind is that rules of the game keep changing. For instance, in chess played on the internet the board has been turned 90 degrees to prevent players from using a computer. When the board is so turned, white king is on the right and black king on the left. One day all chess games may be played this way. In tennis initially to win a set there had to be a two game advantage. Now there is a tie breaker. Similarly the case in most games. Children should be taught all ways a game is played. This way when the official rules change they will be prepared.
Shunnu Puri