Memory is a classic children's game that challenges players to memorize the locations of cards set out in a grid, with the goal of pairing together cards with the same image. While many different versions of Memory have come out over the years (even some off-brand versions), the general directions for playing the game remain the same.
Flip all of the cards over so that the picture sides of the cards are face down. Arrange the cards into a rectangular grid. Keep the grid as uniform as possible, in order to prevent giving unintentional clues to players, which would make it easier to memorize the locations of certain cards.
Have the youngest player take the first turn. The player turns over any two cards in the grid, flipping them all the way over and laying them down with the pictures facing up. The player collects the two cards if the pictures on them are the same, otherwise the two cards are turned back over and it is the next player's turn. A player that makes a match takes another turn, and continues to take turns until they fail to make a match.
Have the next oldest player take his turn in the same manner. Continue to take turns, youngest to oldest, until all of the matches are made.
Have each player count up her matches. The player with the most matches wins.
The object isn't to just randomly flip over cards and hope to make a match, but rather to memorize the locations of the cards as the game goes on. Play the game solo by setting up the cards in the same grid formation. Then count how many turns you have to take, in order to pair up all of the cards. Try to decrease the number of turns it takes you with each additional play of the game. Children too young for the Memory version of the game can still play with the cards: play all of the cards picture side up, and have the young child put together the cards in pairs. This will teach him how to group like items together.