Grade 8 · Data · Scatter Plots and Two-Variable Data

Investigate a Two-Variable Relationship

A scatter plot displays paired values for two continuous variables. Its overall pattern may suggest a strong or weak, positive or negative relationship.

The big idea

Association is evidence, not automatic causation

A trend can support prediction, but an outlier or hidden variable may change the interpretation. The graph must be read with its collection method and context.

Work it through

Analyze study time and quiz score

1. Collect one study-time and one score value from each participant.
2. Plot study time horizontally and score vertically.
3. Describe the direction and strength of the overall cluster, then inspect outliers.
4. State a cautious conclusion and identify what the data cannot prove.

For parents and educators

Ontario curriculum alignment

Grade 8 Mathematics · Strand D: Data

View supported expectations

D1.1 · Data Collection and Organization

Identify situations involving one-variable data and situations involving two-variable data, and explain when each type is needed.
D1.2 · Data Collection and Organization

Collect continuous data to answer questions involving two variables, and organize the data sets in a table of values.
D1.3 · Data Visualization

Select a suitable graph, including a scatter plot, display data with proper sources, titles, labels, and scales, and justify the choice.
D1.4 · Data Visualization

Create an infographic about a data set using appropriate representations, including tables and scatter plots, to tell a data story.
D1.5 · Data Analysis

Use mathematical language including strong, weak, none, positive, and negative to describe relationships between two variables with and without outliers.
D1.6 · Data Analysis

Analyse data in scatter plots and misleading graphs, challenge preconceived notions, draw conclusions, and make convincing arguments and informed decisions.