Lesson Plan: Graphing Linear Equations


Lesson Objectives:

  • Plot points on the coordinate plane
  • Identify the slope and y-intercept of a linear equation
  • Graph linear equations using the slope-intercept form
  • Interpret the meaning of slope and y-intercept in real-life situations

Common Core Standards:

  • 8.EE.B.5: Graph proportional relationships, interpreting the unit rate as the slope of the graph.
  • 8.EE.B.6: Use similar triangles to explain why the slope m is the same between any two distinct points on a non-vertical line in the coordinate plane.

Prerequisite Skills:

  • Plotting points on the coordinate plane
  • Understanding of slope and y-intercept concepts

Key Vocabulary:

  • Coordinate plane
  • Ordered pair
  • Slope
  • y-intercept
  • Slope-intercept form

Warm-up Activity (5 minutes)

For students that need to review graphing points on the coordinate plane review the first example from this video:

https://www.media4math.com/library/39514/asset-preview

Engage students by asking them to plot the following points on a coordinate plane: 

(1, 2)

(2, 4)

(3, 6). 

Use this Desmos activity to graph the points and ask students to notice any patterns. 

https://www.desmos.com/calculator/cq834lfyfp

Then ask them to find additional coordinates that continue the pattern.

Teach (20 minutes)

Definitions

Use the following video definitions to define key terms:

Examples

Demonstrate how to identify the slope and y-intercept from a given linear equation.

Review (10 minutes)

Assess (10 minutes)

Administer a 10-question quiz to assess students' understanding of graphing linear equations. The quiz should include questions on plotting points, identifying slope and y-intercept, graphing linear equations, and interpreting slope and y-intercept in real-life situations.

Quiz

  1. Plot the points (1, 2), (-2, -1), and (3, 4) on the coordinate plane.
    Coordinate grid
  2. Identify the slope and y-intercept of the equation y = 2x + 3.
  3. Graph the equation y = -1/2x + 4 on the coordinate plane.
    Coordinate grid
  4. If the slope of a linear equation is 3 and the y-intercept is -2, what is the equation?
  5. Interpret the meaning of the slope and y-intercept in the equation y = 0.5x + 10. You save fifty cents a day in a piggy bank that already has an amount of money in it.
  6. A line passes through the origin and through (4, 9). What is its equation?
  7. Determine if the point (3, -1) lies on the line represented by the equation y = 2x - 5.
  8. Graph the equation 3y = 6x - 9 on the coordinate plane.
    Coordinate grid
  9. Explain the relationship between the slope of a line and its steepness.
  10. This equation represents a car slowing down every second at a constant speed (in miles per hour): y = -5x +50. What is the car's initial speed? What does the slope represent?

Answers

  1. Coordinate grid
  2. Slope = 2, y-intercept = 3
  3. Linear graph
  4. y = 3x - 2
  5. The slope represents the 50 cents saved a day. The y-intercept is the amount of money initially in the piggy bank (\$10).
  6. y = 9/4x
  7. No, the point (3, -1) does not lie on the line.
  8. Linear graph
  9. The steeper the line, the greater the slope value (positive or negative).
  10. Initial speed is 50 mph. The car slows down by 5 mph every second.

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