How to Play: Whist
How to play: The players form two sets of partners. The dealer deals out all the cards, one at a time, face down, so that each player has 13 cards. The final card, which belongs to the dealer, is turned face up to indicate which suit is trump. The turned up trump remains face up on the table until it is the dealer's turn to play to the first trick. The deal advances clockwise. The player to the dealer's left leads to the first trick. He or she may lead any card in his or her hand. The other players, in clockwise order, each play a card to the trick and must follow suit by playing a card of the suit led if they have one.
A player with no card of the suit led may play any card, either discarding or trumping. The trick is won by the highest card of the suit led, unless a trump is played, in which case the highest trump wins. The winner of the trick leads the next trick. Play continues until all 13 tricks are played, at which point the score is recorded. If no team has enough points to win the game, another hand is played.
The rules: After all tricks have been played, the side that won more tricks scores one point for each trick won in excess of six. When all four players are experienced, it is unusual for the score for a single hand to be higher than two.
How to win: The first team to reach a score of five wins.
What else you need to know: There are several variations of Whist. Pagat has a site that lists all of its different variations.
Related: How to Play: Ninety-Nine
Start by teaching him that it is safe to do so.