Lesson 3: Comparing Groups With Averages

About 30 minutes — Activity-based lesson

What You Will Learn

This lesson covers:

Using the mean to compare two classes, teams, or groups
When is a difference meaningful vs. too small to matter?
Fair comparisons: same measurement, same conditions
Activity: compare class averages for 3 different measurements

Using the mean to compare two classes, teams, or groups

This section covers the key ideas about using the mean to compare two classes, teams, or groups. Discuss with your group or family and explore the concepts together.

When is a difference meaningful vs. too small to matter?

This section covers the key ideas about when is a difference meaningful vs. too small to matter?. Discuss with your group or family and explore the concepts together.

Fair comparisons: same measurement, same conditions

This section covers the key ideas about fair comparisons: same measurement, same conditions. Discuss with your group or family and explore the concepts together.

Activity: compare class averages for 3 different measurements

This section covers the key ideas about activity: compare class averages for 3 different measurements. Discuss with your group or family and explore the concepts together.

Check Your Understanding

1. How do you compare two groups using means?

Answer: Calculate the mean for each group, then compare. If Class A averages 85 on a test and Class B averages 78, Class A scored higher on average — but check if the difference is meaningful.

2. When is a difference between averages meaningful?

Answer: Consider the range of scores and the size of the groups. A 7-point difference between classes of 30 is more meaningful than between classes of 5. Also consider how spread out the scores are.

3. What makes a comparison fair?

Answer: Both groups should be measured the same way, under the same conditions, with the same tools. Comparing indoor and outdoor temperatures with different thermometers is not fair.

4. Can you compare averages of different things?

Answer: Be careful! Comparing the average height of 4th graders to the average weight of 4th graders does not make sense — they measure different things with different units.

Key Takeaways

Using the mean to compare two classes, teams, or groups
When is a difference meaningful vs. too small to matter?
Fair comparisons: same measurement, same conditions
Activity: compare class averages for 3 different measurements

Ready for More?

Next Lesson

Continue to Lesson 4: Averages in the Real World

Start Lesson 4

Session Home

Review all lessons and materials.

Back to Session Home