Linear Relationships

Lesson 13

Math

Unit 5

8th Grade

Lesson 13 of 15

Objective


Write linear equations for parallel and perpendicular lines.

Common Core Standards


Core Standards

  • 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; derive the equation y = mx for a line through the origin and the equation y = mx + b for a line intercepting the vertical axis at b.

Foundational Standards

  • 8.G.A.1
  • 8.G.A.2

Criteria for Success


  1. Understand that parallel lines have the same slope.
  2. Understand that perpendicular lines have opposite and reciprocal slopes.
  3. Write equations for parallel and perpendicular lines using the relationship between slopes.

Tips for Teachers


This lesson is a good opportunity to review and spiral in concepts from throughout the unit. 

Fishtank Plus

Unlock features to optimize your prep time, plan engaging lessons, and monitor student progress.

Anchor Problems

25-30 minutes


Problem 1

Use Graph A and Graph B below to answer the questions.

a.   In Graph A, translate line $$S$$ 3 units up to create parallel line $$S’$$.

  • What is the slope of line $$S'$$?
  • What is the relationship between the slopes of the two parallel lines?

b.   In Graph B, rotate line $$T$$ 90° clockwise about the origin to create perpendicular line $$T’$$.

  • What is the slope of Line $$T$$?
  • What is the slope of Line $$T$$’?
  • What is the relationship between the slopes of the two perpendicular lines?

Guiding Questions

Create a free account or sign in to access the Guiding Questions for this Anchor Problem.

Student Response

Upgrade to Fishtank Plus to view Sample Response.

Problem 2

Lines $$L$$ and $$M$$ are parallel. The equation of line $$L$$ is $${4y=x}$$
Line $$M$$ passes through the point (0, -5).

What is an equation of line $$M$$?

Guiding Questions

Create a free account or sign in to access the Guiding Questions for this Anchor Problem.

Student Response

Upgrade to Fishtank Plus to view Sample Response.

References

Illustrative Mathematics Proportional relationships, lines, and linear equations

Proportional relationships, lines, and linear equations, accessed on Feb. 24, 2018, 10:19 p.m., is licensed by Illustrative Mathematics under either the CC BY 4.0 or CC BY-NC-SA 4.0. For further information, contact Illustrative Mathematics.

Problem 3

Line $$P$$ passes through the points (0, 5) and (4, -3). 

Line $$Q$$ is perpendicular to line $$P$$ and passes through the point (8, -2).

What is an equation for line $$Q$$?

Guiding Questions

Create a free account or sign in to access the Guiding Questions for this Anchor Problem.

Student Response

Upgrade to Fishtank Plus to view Sample Response.

Problem Set

15-20 minutes


Give your students more opportunities to practice the skills in this lesson with a downloadable problem set aligned to the daily objective.

Target Task

5-10 minutes


Line $$A$$ is shown in the graph.

  • Line $$B$$ is parallel to line $$A$$ and passes through the point (2, 3).
  • Line $$C$$ is perpendicular to line $$A$$ and passes through the point (0, -4).

Write an equation for line $$B$$ and for line $$C$$.

 

 

 

Student Response

Upgrade to Fishtank Plus to view Sample Response.

Additional Practice


The following resources include problems and activities aligned to the objective of the lesson that can be used for additional practice or to create your own problem set.

  • Include spiraled problems from earlier in the unit, targeted at where students may need additional concept development or practice.
  • Challenge: Another form of a linear equation is called point-slope form and is represented as $$y-b=m(x-a)$$, where $$m$$ is the slope and $$(a, b)$$ represents a point on the line. Write an equation of the line, in point-slope form, that passes through the points $$(-2, 6)$$ and $$(3, -4)$$
  • Illustrative Mathematics Find the ChangeThis task reviews and helps to solidify concepts of slope and y-intercept; would make a good pair, collaborative problem.
  • Kuta Software Free Algebra 2 Worksheets Review of Linear EquationsMany of these problems ask for standard form; change this to slope-intercept form.
  • MARS Formative Assessment Lesson for Grade 8 Defining Lines by Points, Slopes and EquationsThis lesson pulls together concepts from the last few lessons.

Next

Compare linear functions represented in different ways.

Lesson 14
icon/arrow/right/large

Lesson Map

A7CB09C2-D12F-4F55-80DB-37298FF0A765

Topic A: Comparing Proportional Relationships

Topic B: Slope and Graphing Linear Equations

Topic C: Writing Linear Equations

Request a Demo

See all of the features of Fishtank in action and begin the conversation about adoption.

Learn more about Fishtank Learning School Adoption.

Contact Information

School Information

What courses are you interested in?

ELA

Math

Are you interested in onboarding professional learning for your teachers and instructional leaders?

Yes

No

Any other information you would like to provide about your school?

We Handle Materials So You Can Focus on Students

We Handle Materials So You Can Focus on Students

We've got you covered with rigorous, relevant, and adaptable math lesson plans for free