• Activate prior experience in grade 8 with informally fitting a line to a scatter plot and informally judging its goodness of fit. • Model the relationship with an equation for a line and use it to make predictions. • Represent data on two quantitative variables on a scatter plot. • Describe how two variables on a scatter plot are related. • Interpret the slope and the intercept of a linear model in the context of the data.
(Note: 8.SP.2 and 8.SP.3 are prerequisites, not target standards in this unit. However, they are standards involved in one of the suggested activities.)
In this unit, students build on the statistical work they did in grade 8. Using technology, they represent data on two variables on a scatter plot, find the line of best fit, and interpret the slope and intercepts in context. They assess the fit of a line to data more precisely by plotting and analyzing residuals. Students compare strength of associations between different pairs of variables by interpreting correlation coefficients which they compute using technology. They gain experience in distinguishing between correlation and causality. Modeling is an intrinsic part of the high school statistics and probability standards and of this unit.