**Category:** Chance & Uncertainty and Transformations**Suitable for Grade Level:** Elementary and Secondary

**The Math in this Problem:**

This variation of Tic-Tac-Toe allows the players to place either an X or an O onto the 3×3 grid. The winner is the first player to complete three X’s or three O’s in a row. This twist to the game really forces students to analyze the grid and their opponent’s potential moves, having them strategize more than they would have in the original version.

This game is the same as ordinary tic-tac-toe, except that on each turn a player can choose to play an X or an O. You win if you get three X’s in a row, or three O’s in a row.

What move or moves should the first player make so they always win?

#### Related Game:

Same as the above game except that, after the first move, all placements must be made to a space beside the last space occupied. (If no such space exists, the game is a tie.) Example: the second player wins here:

Is there a sure way for the first or second player to win?