## Plotting Ordered Pairs 1

### Kristy RousseauBay District Schools

#### Description

This lesson serves as an introduction to graphing. Students identify the origin and use the x- and y-axes to plot positive ordered pairs in the coordinate system.

#### Objectives

The student identifies and plots positive ordered pairs (whole numbers) in a rectangular coordinate system (graph).

#### Materials

-1/4- graph paper (one sheet per student)
-Straightedge or ruler
-Pencil

#### Preparations

The teacher needs to:
1. Locate 1/4- graph paper.
2. Prepare an overhead transparency of the graph paper for modeling purposes.
3. Practice plotting the smiley face.
4. Gather rulers and straight edges.

#### Procedures

1. Pass out the graph paper and rulers.

2. Have students fold the paper in half horizontally. (The students will work on the top half of the paper for the first part of the assignment.)

Model the following steps on the overhead as the students are following the example on their papers. Occasionally spot check the students' work to make sure they are on the right track.

3. Have the students draw a straight, horizontal line about three lines up from the center fold. (This will serve as the x-axis.)

4. Have students draw a straight, vertical line about three lines over from the left margin. (This will serve as the y-axis.)

5. After lines have been drawn, identify the axes for the students and have them label the lines accordingly.

6. Draw a point where the two lines intersect and label this as the -origin.-

7. Explain that every point on the graph can be represented as an intersection of the x- and y-axes. Label the origin (0,0) and have the students do the same on their graphs.

8. Next, have the students number the x-axis starting with -0- and moving to the right. Students should continue numbering until they reach -20.-

9. Have the students label the y-axis starting at -0- and moving up until they reach -20.- (Remember to model this on the overhead and spot check students' work.)

10. Explain to the students that they are now looking at a rectangular coordinate graph system and that they will use this system to plot a series of ordered pairs that should create -something worth smiling about.-

11. Write the ordered pair (10,10) on the overhead. (You may want to create a T-Chart with x and y columns under which you list the ordered pair.)

12. -Think out loud- and explain to the students how you know where to plot (10,10) on the graph. Check their work to see that they have correctly plotted this ordered pair. (This point will be the -nose- of a smiley face.)

13. Continue modeling by plotting the positive ordered pairs (8,14) and (8,12). These points will form the left eye of the smiley face when they are connected.

14. Next, plot (12,14) and (12,12) and connect the two points
as in the previous step. The students should now have two eyes and a nose.

15. Finally, have the students plot the following points and connect them to form the smile. Model and scaffold as needed.
*(2,8)
*(3,9)
*(4,10)
*(8,2)
*(12,2)
*(16,10)
*(17,9)
*(18,8)

16. Review with students the origin, and how the x- and y-axes were used to plot ordered pairs.

17. Have the students turn their papers over and write two or three sentences explaining to a younger student how they would plot the ordered pair (2,8).

18. When finished, students should turn their papers in for the teacher to review their process for plotting ordered pairs and their explanation of the process they used. These papers will be passed back for the students to complete -Plotting Ordered Pairs-Part 2.-

#### Assessments

Assess the students' work by
1)checking the students' -smiley faces- for correctly plotted ordered pairs, and
2)reading the students' explanations on the back of the papers.
Look for correct usage of such terms as the x- and y-axes, for correct understandings of how to plot ordered pairs, and correct identification of the ordered pairs. Use this information to gauge the teaching focus in -Plotting Ordered Pairs--Part 2.-

#### Extensions

This lesson is the first lesson in a two-part series introducing the coordinate graph system to students.
For Part 2, see: Plotting Ordered Pairs -Part 2.

Some students may have difficulty following the overhead model. It may benefit them to have a graph that has already been prelabeled and prenumbered.