Graphing Integers

Now that students have been shown how to graph a linear function, it is time for them to try it. Be sure to stress the use of correct mathematical vocabulary. Also stress that the equation, table, and graph are different representations of the same function.

Materials: overhead transparency or poster paper, grid paper and rulers for students

Preparation: Draw a coordinate grid on a transparency or poster paper. Make a copy for each student.

• Say: Yesterday we learned how to make a table and graph for a linear equation like x + 2 = y. Today you will have the opportunity to practice this on your own. If we were going to graph x + 2 = y, what would we do first?
  Students should respond that they need to make a table.

• Ask: What do I do in order to make this table?
  Students should say that they would pick some different values for x and substitute them into the equation and solve it for y. Stress that students should pick both positive and negative values for x to substitute into the equation.

• Ask: Great, now what do we do?
  Students should say that "we now need to graph the ordered pairs we found" or something equivalent to that.

• Say: Using your graph paper, plot the ordered pairs.
  Give students time to plot the points. Have someone graph the points on the overhead transparency grid.

• Ask: What do you notice about the points again? (They seem to lie in a straight line.) Good, now draw a straight line with arrowheads on the ends of the line to indicate that it goes on indefinitely.

• Say: Let's make a list of the steps we need to follow to graph an equation? What is the first step?
  Students should respond that they need to create a table. Write this as step 1 on the board for all to see. Have students copy of this process in their math journals.

• Ask: What is step two?
  Students should say they need to select x-values and substitute them into the equation and find the corresponding y-values. Then they need to record the values in the table and write the ordered pairs.

• Ask: What do we do next?
  Students should say to graph the ordered pairs and draw a straight line connecting them. Be sure to have students note that they need to put the arrowheads on the ends of the lines.

  Give students two more equations to do on their own, while you walk around the room helping individual students.

• Introducing the Concept
• Developing the Concept

• Introducing the Concept
• Developing the Concept