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Linear or not?: 8th grade math

Linear functions y = mx + b vs. nonlinear. A free 8th grade lesson plan, a question set with answers and a printable sheet with its key. Copy it and make it yours.

Lesson plan

Goal

  • Students can do this: linear functions y = mx + b vs. nonlinear.

Teach (10 min)

  • In y = mx + b, m multiplies x: it is the slope. b is added on its own: it is where the line crosses the y-axis.
  • In y = 3x − 5 the slope is 3 and the y-intercept is −5. Keep the sign with the number.
  • Work one example on the board while students say each step aloud, then do one together.

Practise (15 min)

  • Students work the printable sheet in pairs, then alone.
  • Or practise it as a game with no sign-up: https://peabody.kids/math/lines.slopeIntercept?lesson=8-lines-slopeintercept-1&at=8

Exit ticket (5 min)

  • Three questions on a slip:
  • 1. What is the slope of the line y = x + 6?
  • 2. What is the y-intercept of the line y = 3x + 2?
  • 3. What is the slope of the line y = 5x + 5?

Question set

10 questions that read in words, easiest first. Questions that need a picture are on the printable sheet below.

  1. What is the slope of the line y = x + 6?
  2. What is the y-intercept of the line y = 3x + 2?
  3. What is the slope of the line y = 5x + 5?
  4. What is the slope of the line y = 3x − 4?
  5. What is the slope of the line y = 4x − 3?
  6. What is the y-intercept of the line y = 5x + 3?
  7. What is the y-intercept of the line y = 3x + 8?
  8. What is the slope of the line y = 4x + 7?
  9. What is the slope of the line y = −4x − 8?
  10. What is the y-intercept of the line y = 7x − 3?
Answers
  1. 1
  2. 2
  3. 5
  4. 3
  5. 4
  6. 3
  7. 8
  8. 4
  9. −4
  10. −3

Printable sheet

Name: ____________________   Date: ____________

Linear or not? (8th grade)

  1. What is the slope of the line y = 6x + 4?
  2. What is the slope of the line y = x − 8?
  3. What is the slope of the line y = 3x − 6?
  4. What is the y-intercept of the line y = 3x − 2?
  5. What is the y-intercept of the line y = 6x + 8?
  6. The graph shows the line y = mx + b. Where does the line cross the y-axis? Give the y-intercept b.
    −6−6−5−5−4−4−3−3−2−2−1−1112233445566xy
  7. What is the y-intercept of the line y = 6x + 6?
  8. The graph shows the line y = mx + b. Where does the line cross the y-axis? Give the y-intercept b.
    −6−6−5−5−4−4−3−3−2−2−1−1112233445566xy
  9. What is the slope of the line y = 5x − 6?
  10. The graph shows the line y = mx + b. Where does the line cross the y-axis? Give the y-intercept b.
    −6−6−5−5−4−4−3−3−2−2−1−1112233445566xy
  11. What is the slope of the line y = 2x − 3?
  12. The graph shows the line y = mx + b. Where does the line cross the y-axis? Give the y-intercept b.
    −6−6−5−5−4−4−3−3−2−2−1−1112233445566xy
Key
  1. 6
  2. 1
  3. 3
  4. −2
  5. 8
  6. −4
  7. 6
  8. 1
  9. 5
  10. 2
  11. 2
  12. 4

Written by Peabody from its own skill pages. Free, no ads, no sign-in. Children can practise this on Peabody. More from teachers: teacher-shared resources.