A coordinate plane is a flat grid with two number lines crossing at right angles. Once you know how to read it, you can plot any point, line or shape. This guide uses a printable coordinate plane.
The parts of the plane
- x-axis: the horizontal line. Positive numbers are to the right of the origin, and negative numbers to the left.
- y-axis: the vertical line. Positive numbers are above the origin, and negative numbers below.
- Origin: where the two axes cross, written (0, 0).
- Quadrants: the four regions made by the axes, numbered I to IV counter-clockwise starting at the top right.
Reading an ordered pair
A point is written (x, y). The first number tells you how far to move along the x-axis, and the second tells you how far to move up or down. A common memory aid is that you walk along the hall before you go up the stairs: x first, then y.
Plot (3, -2) in four steps
- Start at the origin.
- Move 3 units to the right, since x is positive.
- Move 2 units down, since y is negative.
- Mark the point and label it. It sits in quadrant IV.
Which quadrant?
| Quadrant | Sign of x | Sign of y |
|---|---|---|
| I | + | + |
| II | − | + |
| III | − | − |
| IV | + | − |
Try it
Plot A(2, 1), B(2, 4) and C(5, 1), then join them. You have drawn a right triangle. Reflect it across the y-axis by changing the sign of each x value, and you get A'(-2, 1), B'(-2, 4) and C'(-5, 1).
Which paper to use
Use four-quadrant paper when the problem has negative values. When everything is positive, as in most statistics and real-world data, first-quadrant paper gives you a larger scale. Choose the first-quadrant preset in the coordinate plane generator.