Plotting Points is the first of four self-paced lessons in the “The Coordinate Plane” section of KET’s GED^{®} Geometry Professional Development Online Course. This lesson focuses on the fundamentals needed to plot points on a coordinate grid.

NOTE: This course was created based on the 2002 GED^{®} math test. The geometry instruction in this course is still valid, however, for up-to-date information about the 2014 GED^{®} math test, please visit KET’s GED^{®} Test Info: Mathematics online course.

On the GED^{®} Mathematics Test, students need to answer questions that require them to plot points on the coordinate plane.

They will need to understand the coordinate plane, consisting of an x-axis and a y-axis.

They will also need to know how to plot points, based on an ordered pair of coordinates.

This lesson focuses on the fundamentals needed to plot points on a coordinate grid. Some students may be unfamiliar with the concept of positive and negative numbers on a number line, which is a prerequisite concept for this skill.

2The Coordinate Plane

Watch the video to learn about the coordinate plane.

The Coordinate Plane

Video: 1m 31s

A coordinate plane is a flat surface divided by two number lines into four quadrants. The point where the number lines intersect is called the origin, which is located at zero on both number lines.

Question The grids on the left show three coordinate planes. Which coordinate plane is correctly labeled?

Step 1 Look at Grid 1. Ask yourself, “Do the locations of the x-axis, y-axis, and positive and negative numbers match the descriptions above?”

No, the x-axis should be the horizontal axis, and the y-axis should be the vertical axis.

Step 2 Look at Grid 2. Ask yourself the same question.

Grid 2 is incorrect. The positive numbers should be above the origin and to the right of the origin.

Step 3 Finally, look at Grid 3.

The axes and numbers are correctly labeled in Grid 3.

Answer Grid 3

3Recognizing Plotted Points

For every point on a coordinate plane, there is an address called an ordered pair that gives the coordinates of a point. The x-coordinate defines the position of the point on the x-axis. The y-coordinate defines the position of the point on the y-axis.

An ordered pair is always expressed in the order (x, y). If the first number in the ordered pair is positive, the point is located to the right of the y-axis. If it is negative, the point is to the left. If the second number is positive, the point is located above the x-axis. If it is negative, the point is below the x-axis.

Question What are the coordinates of point P? Write the ordered pair for point P.

Step 1 Start at the origin (0, 0), the point where the x and y axes intersect. Move right until you are above point P.

Step 2 Write the first coordinate. You moved 3 units to the right on the x-axis. You moved in the positive direction.

(3, ___)

Step 3 Next, move down until you reach point P.

Step 4 Write the second coordinate. You moved 4 units down on the y-axis. You moved in the negative direction.

(3, –4)

Step 5 Check: Point P is directly below 3 on the x-axis, and it is directly across from –4 on the y-axis.

Answer (3, –4)

4Sample GED Questions

Directions: There are two questions on this page. Each will appear in the blue rectangle below. Click on Question 1 to see the first question, and then select your answer. Click on Question 2 to see the second question, and select your answer. As you solve these problems, consider how you would work through them with your students.

How could you help students see the relationship of ordered pairs to the four quadrants of the coordinate plane?

The Coordinate Plane: Plotting Points Skill Review

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Printable Resource

In this lesson you have learned about the coordinate plane. This review consists of key terms and concepts with which you will need to be familiar. Click the view button on the left to access a review sheet.

Below you will also see a Classroom Connection with suggestions for linking this geometry content with your instruction.

Assign directly to your students using the code or link above, without having them log in. Simply tell your students to go to
www.pbsstudents.org and enter the Assignment Code, or click on the Assignment URL to share the assignment as a link.