A coordinate grid is a series of vertical and horizontal lines that form a pattern of squares on the page; each grid line has a number or coordinate. Coordinate grids are useful for graphing positions of numbers to see patterns of lines and curves.
One horizontal line in the grid serves as the x-axis, and a vertical line forms the y-axis. The point where they meet is the origin, which has the coordinates 0,0. The first vertical line to the right of the y-axis has the coordinate 1 on the x-axis; the next one has the x-coordinate 2, and so on. The vertical line to the left of the y-axis has the x-coordinate -1; the next line to the left is -2.
The first horizontal line above the x-axis has the coordinate 1 on the y-axis, and the line above it has the y-coordinate 2. The y-coordinate of the horizontal line just below the x-axis is -1; the line below it is -2.
An ordered pair represents the position or coordinates of a point on the grid. The ordered pair (5, 2) represents the point five lines to the right of the x-axis and two lines above the y-axis.