In the previous lesson, students interpreted the mean as a fairshare value—i.e., what each group member would have if all the values are distributed such that all members have the same amount. In this lesson, students use the structure of the data (MP7) to interpret the mean as the balance point of a numerical distribution. They calculate how far away each data point is from the mean and study how the distances on either side of the mean compare.
Students connect this interpretation to why we call the mean a measure of the center of a distribution and, through this interpretation, begin to see how the mean is useful in characterizing a “typical” value for the group. Students continue to practice calculating the mean of a data set (MP8) and interpreting it in context (MP2).
Lesson overview
 10.1 Warmup: Which One Doesn’t Belong: Division (5 minutes)
 10.2 Activity: Travel Times (Part 1) (15 minutes)
 10.3 Activity: Travel Times (Part 2) (15 minutes)
 Lesson Synthesis
 10.4 Cooldown: Text Messages (5 minutes)
Learning goals:
 Calculate and interpret (orally and in writing) distances between data points and the mean of the data set.
 Interpret diagrams that represent the mean as a “balance point” for both symmetrical and nonsymmetrical distributions.
 Represent the mean of a data set on a dot plot and interpret it in the context of the situation.
Learning goals (student facing):

Let's look at another way to understand the mean of a data set.
Learning targets (student facing):
 I can describe what the mean tells us in the context of the data.
 I can explain how the mean represents a balance point for the data on a dot plot.
Glossary:
 measure of center  A measure of center is a value that seems typical for a data distribution. Mean and median are both measures of center.
 Access the complete Grade 6 glossary.
IM 6–8 Math was originally developed by Open Up Resources and authored by Illustrative Mathematics, and is copyright 20172019 by Open Up Resources. It is licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0). OUR's 6–8 Math Curriculum is available at https://openupresources.org/mathcurriculum/.
Adaptations and updates to IM 6–8 Math are copyright 2019 by Illustrative Mathematics, and are licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0).
Adaptations to add additional English language learner supports are copyright 2019 by Open Up Resources, and are licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0).
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