The mathematical purpose of this lesson is for students to understand what makes a linear model a better or worse fit for data displayed using a scatter plot. In the associated Algebra 1 lesson, students create lines of best fit and interpret the -intercept of a linear model in terms of the situation. Students model with mathematics (MP4) when they determine the line that best fits the data. Students then construct viable arguments (MP3) when they explain the goodness of fit of lines created using various methods.