NY Next Generation Math NY-8.SP.2
The Standard
Understand that straight lines are widely used to model relationships between two quantitative variables. For scatter plots that suggest a linear association, informally fit a straight line, and informally assess the model fit by judging the closeness of the data points to the line.
New York State Next Generation Mathematics Learning Standards
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students draw an informal straight line through a scatter plot that suggests a linear association. They judge how well the line models the data by examining how close the points lie to it.
What Mastery Looks Like
- A student places a line through the center of a linear point cloud with points reasonably balanced above and below. The student explains that smaller point-to-line distances indicate a better informal fit.
Common Misconceptions
- Students may connect the data points, force a line onto a nonlinear pattern, or draw through only two convenient points. They may also judge fit from one point instead of the overall closeness.
How to Assess It
- Show a scatter plot with a clear linear association. Ask students to draw an informal fit line and cite two features that support or weaken its fit.
Lesson moves
Ways to Teach It
Place a transparent ruler over a scatter plot, adjust it through the point cloud, and mark a balanced informal fit line.
Ask students which of two proposed lines better fits the same scatter plot and what visual evidence supports the choice.
Play line-fit challenge by ranking several candidate lines from best to worst and defending the order.
Graph paired plant-growth data, fit a line informally, and describe how closely the line models the measurements.
Keep exploring
Related Standards
- NY-8.F.4
Construct a function to model a linear relationship between two quantities. Determine the rate of change and initial value of the function from a description of...
- NY-8.SP.1
Construct and interpret scatter plots for bivariate measurement data to investigate patterns of association between two quantities. Describe patterns such as cl...
- NY-8.SP.3
Use the equation of a linear model to solve problems in the context of bivariate measurement data, interpreting the slope and intercept.
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