You probably already know how to play Tic-Tac-Toe. It's a really simple game, right? That's what most people think. But if you really wrap your brain around it, you'll discover that Tic-Tac-Toe isn't quite as simple as you think!

Tic-Tac -Toe (along with a lot of other games) involves looking ahead and trying to figure out what the person playing against you might do next.

RULES FOR TIC-TAC-TOE

1. The game is played on a grid that's 3 squares by 3 squares.

2. You are X , your friend (or the computer in this case) is O . Players take turns putting their marks in empty squares.

3. The first player to get 3 of her marks in a row (up, down, across, or diagonally) is the winner.

4. When all 9 squares are full, the game is over. If no player has 3 marks in a row, the game ends in a tie.

To beat the computer (or at least tie), you need to make use of a little bit of strategy. Strategy means figuring out what you need to do to win.

Part of your strategy is trying to figure out how to get three X s in a row. The other part is trying to figure out how to stop the computer from getting three O s in a row.

After you put an X in a square, you start looking ahead. Where's the best place for your next X ? You look at the empty squares and decide which ones are good choices—which ones might let you make three X s in a row.

You also have to watch where the computer puts its O . That could change what you do next. If the computer gets two O s in a row, you have to put your next X in the last empty square in that row, or the computer will win. You are forced to play in a particular square or lose the game.

If you always pay attention and look ahead, you'll never lose a game of Tic-Tac-Toe. You may not win, but at least you'll tie.