Materials: Cartesian Coordinate Grids. Pencils
Procedures: Players alternate putting X and O at the intersection points
by giving the coordinates of the point they choose to use. The
winner is the first player to place four of her marks in a row
along (a) a vertical line, (b) a horizontal line, or (c) a slanted
line. The player must announce the coordinates of the point she
desires to use and then place her mark. She must use the first
numbers she announces -- no changing.
Note: Keep a ruler handy to settle arguments (Slope should help determine
if the points lie on a line). Students generally play vertically or
horizontally at the beginning but soon discover other segments. This is
a good activity for review of point plotting and as an introduction to slope.
This game can be introduced to a class by dividing the class into two teams.
Members of each team alternate giving coordiantes. Do not attempt to
teach the strategy of the game. Students will discover this quickly.