# Dispersion of Data (Day 1 of 2)

## Objective

SWBAT describe the spread of the data based on interquartile range, range, outliers, variance, and standard deviation.

#### Big Idea

To understand the meaning of dispersion(spread of the data) and to gain the correct vocabulary to describe it.

## Warm Up

15 minutes

I begin the lesson with this Warm Up.  I expect the Warm Up to take about 10 minutes for the students to complete and for me to review with the students.  In this Warm Up, I provide students with a set of data of free throw percentages of top NBA players.

In this lesson, students will be finding the following to describe the Dispersion (spread) of the data:

1.  Range

2.  Interquartile Range

3.  Outliers/Gaps

4.  Variance

5.  Standard Deviation (of a sample)

In this Warm Up, I ask students to find the Range and Interquartile Range to describe the spread of the data.  Students have previously learned to find Range and Interquartile Range, so the Warm Up should be a review.  After the Warm Up, we will continue to use the same set of data through the next section of this lesson.  In the next section of this lesson, we will use the other three ways given above to describe Dispersion.

## Power Point

20 minutes

After reviewing the Warm Up with the students, I hand each student a copy of the Power Point for them to use to write notes. We continue using the data from the Warm Up of the free throw percentages of the top NBA players.  I project the Power Point on the Board and quickly review the formulas for Range and Interquartile range that we already found in the Warm Up. Then we begin discussing Outliers, and move forward to Variance, and Standard Deviation.

I demonstrate the work that I did with the students on Dispersion in the video below.

## Partner Work

15 minutes

In the closure of today's lesson, I assign each set of table partners an additional data set on the salaries of military personnel.  I instruct students to describe the dispersion of the data using all of the different ways that we have learned today.

This includes:

1.  Range

2.  Interquartile Range

3.  Outliers/Gaps

4.  Variance

5.  Standard Deviation

Students use the remaining of the period to begin working on the data set.  This is a two day lesson, and students will complete the activity at the beginning of the period the following day.