Now that the students have seen you graph points on the coordinate plane, it is time for them to try it. Be sure to have students use the proper vocabulary in explaining what they do.
Materials: overhead transparency or poster paper; grid paper and rulers for students
Preparation: Draw a coordinate grid on a transparency or poster paper.
Pass out grid paper with points A H marked on them as shown on the grid at the bottom of this page. (There are 2 points in each quadrant.) Put a transparency with the same grid on the overhead for the students to see. Point to points A and F as you ask the questions below.
- Ask: What are the coordinates for this point? Explain how you found the coordinates.
After doing this for both points A and F, have the class find the coordinates for the other six points. Have students explain how they found the coordinates.
- Ask: Where is the point (0, -4) on the plane? Explain.
Do several other points found on both the x- and y-axes.
- Say: Plot on your graph the following points: (-3, 2), (3, -1), (2, 2), and (-4, -6).
Have a volunteer plot the points on the overhead after students have plotted them at their desks.
- Say: Look at the points in the first quadrant, what can you tell me about the x- and y-coordinates for those points? (They are both positive numbers.) Now look at the points in the second, third, and fourth quadrants. See if you can tell me anything about the x- and y-coordinates for those points.
After students have told you about the x- and y-coordinates in each of the quadrants, ask questions like the following.
- Ask: In what quadrant would you find a positive x-coordinate and a negative y-coordinate? (IV) In what quadrant would you find a point with a negative x- and y-coordinate? (III) Where would you find a point with a zero x-coordinate and a negative y-coordinate? (Lower half of the y-axis) What ordered pair corresponds to the origin? (0, 0)
- Ask: Who can summarize for me the information about the signs of the coordinates in the first quadrant? Second quadrant? Third quadrant? Fourth quadrant? What about the points on the two axes?
(Click on the graph to see a full-page version of it.)
Graphing Linear Equations