A Cartesian coordinate system, also known as rectangular coordinate system, is a set of two number lines that can be used to plot points and graph lines. The horizontal line is called x-axis and the vertical line is called y-axis.

A point is represented by a pair of numbers (x, y) and an example of a point is (1, 5). First start with the interactive lesson below.

Understanding the Four Quadrants

The coordinate grid is divided into four quadrants by the x and y axes. Each quadrant has different rules for the signs (+ or -) of x and y coordinates.

Quadrant 1 Point: (3, 2)

• x is positive (3 units right)

• y is positive (2 units up)

Remember: In Quadrant 1, both coordinates are positive (+,+)

Quadrant 2 Point: (-4, 3)

• x is negative (4 units left)

• y is positive (3 units up)

Remember: In Quadrant 2, x is negative and y is positive (-,+)

Quadrant 3 Point: (-2, -3)

• x is negative (2 units left)

• y is negative (3 units down)

Remember: In Quadrant 3, both coordinates are negative (-,-)

Quadrant 4 Point: (4, -2)

• x is positive (4 units right)

• y is negative (2 units down)

Remember: In Quadrant 4, x is positive and y is negative (+,-)

Explore the Coordinate System

Tap or click anywhere on the grid to place a point!

Find this point:

Current Point: (0, 0)

Quadrant: Origin

Score: 0 correct out of 0 attempts

How to plot points using vertical and horizontal lines

Locate point (2,3).

x = 2 and y = 3

Draw a vertical line at x = 2 and draw a horizontal line at y = 3

Where the two lines meet or intersect, is your point (in red)

Locate point (-3, 1)

Draw a vertical line at x = -3 and draw a horizontal line at y = 1

The intersection of the two lines is your point.

Locate point (-4, -4)

Draw a vertical line at x = -4 and draw a horizontal line at y = -4

Tricky cases are when points are located on the x-axis or the y-axis. Students usually get confused, so study the following two examples carefully.

Locate point (2,0)

Draw a vertical line at x = 2 and draw a horizontal line at y = 0.

Notice that when y = 0, your horizontal line is on the x-axis

Important point to remember:

When y = 0, your point is always located on the x-axis

Locate point (0, -3)

Draw a vertical line at x = 0 and draw a horizontal line at y = -3.

Notice that when x = 0, your vertical line is on the x-axis

Important point to remember:

When x = 0, your point is always located on the y-axis