Playing Board and Materials
Each Scrabble game comes with a 15x15-tile game board, a tile rack for each player and 100 lettered tiles, two of which are blank on both sides. These two can be used to represent the letter of the holder's choice. To start the game, each player draws one tile and shows it to the other players. The player with the letter closest to "A" will go first. In case of a tie, the players who are tied draw again. Each player keeps her letter and then draws six more for a total of seven letters.
Game Play
On your turn, you can either use your tiles to play a word, trade one or more of your tiles or skip your turn completely. To play a word, you must build off of tiles already on the board. You may only play tiles in one direction--left to right or up and down--and your tiles must be adjacent to each other so you cannot play off different ends of a word. After you play your tiles, draw as many tiles as you need to so that you have seven tiles in your rack.
Scoring
Every time a player plays a word, he gets points equal to the value of the letters in the word or words that are formed. If a word covered both a bonus letter and bonus word score, such as a double letter and a triple word, the letter is doubled first and then the doubled letter value is used in calculating the triple word score. Bonus tiles are only counted the first time word is played on them. For example, if an X, worth eight points, is played on a double letter, is it worth 16 points that turn. If a future word uses that X, it is only worth eight in that word because it is not the first time the square has been used. If you use all seven of your tiles in one turn you get a 50-point bonus in addition to any points you earned from the word.
If you doubt that a word your opponent plays is legitimate, you may challenge it. If it is not a word, the tiles are retracted and your opponent loses his turn. If it is a word, you lose your turn.
Ending the Game
The game ends when either no tiles remain to be drawn and a player uses all of her tiles or when each player passes two times in a row. If a player uses all of her tiles, the other players total the value of the letters left on their racks. The player who went out adds the value of those tiles to her score and the other players subtract the number of points they had remaining from their score. For example, if player A went out, player B had a Z (10 points) and a C (three points) left and player C had an A (one point) and a K (five points) left, player A would add 19 points to her score, player B would subtract 13 points from her score and player C would subtract six points from her score. If each player passes twice in a row, each player subtracts the value of her remaining letters from her score. The player with the most points is declared the winner.