Resources/Scatter plots and trend lines
Grade 8•Printable worksheet + answer key•CC0 license

Scatter plots and trend lines

Interpret association, identify outliers, and make predictions.

Students analyze scatter plots for correlation, identify outliers, and use trend lines to estimate values.

Print-ready worksheet with answer key and quick teaching tips.

Grade 80 problems10 minAnswer key included
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Ready-to-teach

Clear steps, examples, and practice in one printable page.

Misconception-proof

Highlights common mistakes and how to fix them quickly.

Open license

CC0: free to copy, adapt, and share without attribution.

Quick overview

This free scatter plots worksheet for grade 8 (8.SP) covers positive, negative, and no correlation with trend line predictions.

Lesson plan snapshot

15-20 min
  • Warm-up (3 min): review correlation types with quick examples.
  • Model (5 min): solve the worked example together.
  • Guided practice (5 min): complete problems 1-3 as a group.
  • Independent practice (7 min): finish the remaining problems.

Materials: graph paper, pencil

Learning targets

  • Classify correlation as positive, negative, or none.
  • Identify outliers that do not fit the pattern.
  • Use a trend line to estimate missing values.

Step-by-step approach

  1. 1Scan the overall pattern: up, down, or scattered.
  2. 2Check for points far from the main cluster (outliers).
  3. 3Use the trend line to estimate values at a given x.
  4. 4Explain what the relationship means in words.

Common mistakes

Mistake

Claiming correlation proves causation.

Try instead

Correlation shows a relationship, not a cause-and-effect rule.

Mistake

Letting an outlier pull the trend line.

Try instead

Draw a line that balances points above and below the main cluster.

Mistake

Reading x and y values backward.

Try instead

Move across for x, then up for y.

Worked example

Guided
Use the trend line y=2x+3y = 2x + 3 to estimate y when x = 4.
  1. Substitute x = 4 into the equation.
  2. Compute y = 2(4) + 3 = 11.
Answer: 11

Related resources

Coordinate plane

Plot points and read ordered pairs.

View resource

Functions

Identify linear and nonlinear relationships.

View resource

Word problems

Translate relationships into context.

View resource

Practice problems

10 problems • 15 min

Printable worksheet
  1. 1
    A trend line is y=1x+5y = 1x + 5. If y = 8, estimate x.
  2. 2
    A scatter plot compares practice days (x) and free throws made (y). What does the point (5, 65) represent?
  3. 3
    A scatter plot has points (1, 27), (3, 6), (1, 5), (2, 5), (6, 11), (5, 8). Which point is an outlier?
  4. 4
    A scatter plot compares hours studied (x) and test score (y). What does the point (7, 74) represent?
  5. 5
    A trend line for a scatter plot is y = x + 4. Predict y when x = 3.
  6. 6
    What type of correlation is most likely? Shoe size and favorite color are compared.
  7. 7
    A trend line for a scatter plot is y = x + 5. Predict y when x = 5.
  8. 8
    A trend line is y=1x+5y = 1x + 5. If y = 7, estimate x.
  9. 9
    A scatter plot compares pages read (x) and quiz score (y). What does the point (6, 80) represent?
  10. 10
    A scatter plot has points (4, 12), (6, 17), (3, 12), (1, 8), (5, 15), (1, 27). Which point is an outlier?

Answer key

10 answers
  1. 11) 3
  2. 22) 5 days, 65 shots
  3. 33) (1, 27)
  4. 44) 7 hours, 74 points
  5. 55) 7
  6. 66) No correlation
  7. 77) 10
  8. 88) 2
  9. 99) 6 pages, 80 points
  10. 1010) (1, 27)

Teacher tips

  • THave students describe the relationship in words before labeling it.
  • TUse a ruler to sketch trend lines through the data cluster.
  • TDiscuss why outliers should be checked but not ignored.

Parent tips

  • PAsk your child to explain whether the points trend up or down.
  • PPractice with real data like study time and quiz scores.
  • PEncourage them to estimate, not calculate exact predictions.

Open license

You are free to copy, adapt, and share these materials. No attribution required. Released under Creative Commons CC0 1.0 (public domain).