In this Grade 8 lesson from Big Ideas Math Course 3, students learn how to construct and interpret scatter plots by graphing two related data sets as ordered pairs in a coordinate plane. Students identify positive linear, negative linear, and nonlinear relationships between variables such as weight and circumference of sports balls or student absences and final grades. The lesson also introduces how to read specific data values from a scatter plot and use patterns in the data to make predictions.
Section 1
Understanding Scatter Plots and Bivariate Data
Bivariate data consists of pairs of values for two different variables. A scatter plot is a graph that displays these pairs of data as points on a coordinate plane to show the relationship between the two variables.
Section 2
Choosing Appropriate Scales for Scatter Plot Axes
When creating a scatter plot, choose scales that:
(1) include all data values with some space beyond the minimum and maximum,
(2) use convenient intervals that make the graph easy to read, and
(3) result in a plot that uses most of the available space without being cramped or too spread out.
Section 3
Procedure: Plotting Points on a Scatter Plot
A scatter plot is constructed by converting two-variable data into ordered pairs where represents the first variable and represents the second variable, then plotting these points on a coordinate plane with appropriate scales.
Section 4
Interpreting Relationships in Scatter Plots
Four types of relationships can be identified in scatter plots:
Positive Linear - points form a pattern where as increases, increases along an approximate straight line;
Negative Linear - points form a pattern where as increases, decreases along an approximate straight line;
Nonlinear - points form a curved pattern (parabolic, exponential, etc.);
No Relationship - points show no discernible pattern or trend.
Expand to review the lesson summary and core properties.
Section 1
Understanding Scatter Plots and Bivariate Data
Bivariate data consists of pairs of values for two different variables. A scatter plot is a graph that displays these pairs of data as points on a coordinate plane to show the relationship between the two variables.
Section 2
Choosing Appropriate Scales for Scatter Plot Axes
When creating a scatter plot, choose scales that:
(1) include all data values with some space beyond the minimum and maximum,
(2) use convenient intervals that make the graph easy to read, and
(3) result in a plot that uses most of the available space without being cramped or too spread out.
Section 3
Procedure: Plotting Points on a Scatter Plot
A scatter plot is constructed by converting two-variable data into ordered pairs where represents the first variable and represents the second variable, then plotting these points on a coordinate plane with appropriate scales.
Section 4
Interpreting Relationships in Scatter Plots
Four types of relationships can be identified in scatter plots:
Positive Linear - points form a pattern where as increases, increases along an approximate straight line;
Negative Linear - points form a pattern where as increases, decreases along an approximate straight line;
Nonlinear - points form a curved pattern (parabolic, exponential, etc.);
No Relationship - points show no discernible pattern or trend.