Lesson 2: Measuring Spread: Range and More

About 30 minutes — Activity-based lesson

What You Will Learn

This lesson covers:

Range: the simplest measure of spread (max - min)
Why range alone is not enough: it is affected by outliers
What a 'typical' spread looks like vs. an unusual one
Activity: calculate the range and describe the spread of 5 datasets

Range: the simplest measure of spread (max - min)

This section covers the key ideas about range: the simplest measure of spread (max - min). Discuss with your group or family and explore the concepts together.

Why range alone is not enough: it is affected by outliers

This section covers the key ideas about why range alone is not enough: it is affected by outliers. Discuss with your group or family and explore the concepts together.

What a 'typical' spread looks like vs. an unusual one

This section covers the key ideas about what a 'typical' spread looks like vs. an unusual one. Discuss with your group or family and explore the concepts together.

Activity: calculate the range and describe the spread of 5 datasets

This section covers the key ideas about activity: calculate the range and describe the spread of 5 datasets. Discuss with your group or family and explore the concepts together.

Check Your Understanding

1. What is the range?

Answer: The difference between the highest and lowest values. If test scores go from 65 to 98, the range is 98 - 65 = 33 points.

2. Why is range limited?

Answer: Because it only uses two values (max and min) and is heavily influenced by outliers. One extreme score can make the range huge.

3. What does a small range mean?

Answer: Data points are close together — the group is consistent. A class with scores from 78 to 85 (range = 7) is very consistent.

4. What does a large range mean?

Answer: Data points are spread out — the group is varied. A class with scores from 45 to 100 (range = 55) has very different performance levels.

Key Takeaways

Range: the simplest measure of spread (max - min)
Why range alone is not enough: it is affected by outliers
What a 'typical' spread looks like vs. an unusual one
Activity: calculate the range and describe the spread of 5 datasets

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