Unit 6, Lesson 4
Fitting a Line to Data
Grade 8
Preparation
Lesson Narrative
In this lesson, student focus becomes more holistic and they begin to see a set of data points as a single thing that can be analyzed, not just as a bunch of disconnected points. For the first time students see that sometimes the relationship between two variables can be modeled with a line (MP4), although they continue to analyze the connections between the scatter plot and the line by comparing individual points. As they zoom out and see these connections, students begin to see the structure of the scatter plot (MP7) and to use that structure to reason abstractly and quantitatively (MP2) to connect the points to real situations.
- Compare and contrast (orally) values in a data set with predictions made using a given line.
- Comprehend that a model of data, such as a line of fit, can be used to predict values that are not given in the data.
- Identify (orally) obvious outliers on a scatter plot.
Let’s look at the scatter plots as a whole.
Required Preparation
For the digital version of the activity, acquire devices that can run the applet.
For the digital version of the activity, acquire devices that can run the applet.
An outlier is a data value that is far from the other values in the data set.
This scatter plot shows 1 outlier.
A scatterplot. Horizontal, from 20 to 32, by 2's, labeled foot length in centimeters. Vertical, from 7 to 12, by 1’s, labeled foot width in centimeters. 20 dots trend upward and to the right. Line drawn, trends linearly upward and right with 11 dots above lie and 9 below. No dots lie on the line. The line begins at about point 21 point 9 comma 9 and ends at about 31 point 25 comma 11 point 5.