This Instructional Activity is a part of the Lesson 5, Unit 6, Grade 8. In this activity, students begin to determine what makes a good model for data. They compare two different lines with the same data set to determine which model fits the data better. A formal, quantitative discussion of lines that best fit data will come in later grades. At this stage, students are only asked to informally determine whether the line fits the data well based on how close the points are to the line. Display the scatter plot for all to see and ask students, "What do you notice?