Unit Plan 28 (Grade 8 Math): Patterns in Bivariate Data—Scatter Plots
8th graders construct and interpret scatter plots to explore relationships between two variables. They identify direction, form, strength, clusters, and outliers, and compare patterns across data sets using precise, evidence-based descriptions.
Focus: Construct and interpret scatter plots; describe patterns (clustering, positive/negative association, outliers).
Grade Level: 8
Subject Area: Mathematics (Statistics & Probability • Data Analysis)
Total Unit Duration: 5 sessions (one week), 45–60 minutes per session
I. Introduction
This week launches students into bivariate data—pairs of numerical measures for the same individuals or objects (for example, study time and score, height and arm span). Students will create scatter plots from real or curated data, choose sensible scales, and describe patterns using grade-level language: positive/negative association, linear vs nonlinear tendency, strength, clusters, and outliers. Emphasis is on clear visuals, precise descriptions, and evidence-based claims from the graph.
Essential Questions
- How do I turn a two-variable data set into a clear, readable scatter plot?
- What story does the plot tell—direction, form, strength, clusters, and outliers—and how do I say it precisely?
- How can I compare two scatter plots of related contexts to draw reasonable conclusions?
II. Objectives and Standards
Learning Objectives — Students will be able to…
- Identify bivariate numerical data, select appropriate axes and scales, and construct accurate scatter plots.
- Describe patterns of association:
- Direction: positive, negative, or no clear association.
- Form: roughly linear or clearly nonlinear/curved.
- Strength/variability: tight vs widely scattered points.
- Features: clusters and outliers (and their possible effects).
- Compare and contrast patterns across two data sets displayed in scatter plots.
- Communicate interpretations with complete sentences referencing the graph (axes, units, trends, notable points).
Standards Alignment — CCSS Grade 8
- 8.SP.1: Construct and interpret scatter plots for bivariate measurement data to investigate patterns of association between two quantities (describe clustering, outliers, positive/negative association, linear/nonlinear).
Success Criteria (student-friendly)
- I can create a labeled scatter plot with sensible scales and correctly plotted points.
- I can describe the direction, form, strength, clusters, and outliers I see, with evidence from the plot.
- I can compare two scatter plots and explain how their patterns are alike/different.
- I can write a short, clear interpretation that someone else can follow.