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Dot Plots

Lesson # 4

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2019 Open Up Resources |

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Let’s investigate what dot plots and bar graphs can tell us.

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Today’s Goals

I can identify the spread and center of data from a dot plot.

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Pizza Toppings (Part 1)

Warm Up

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Complete the activity with your partner
Compare your frequency tables with another group

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Pizza Toppings (Part 2)

Activity 1

Think Pair Share
MLR2: Collect & Display

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Work quietly (4-5 min)
Share your responses with your partner (1-2 min)

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Are you ready for more?

Think of a statistical question that can be answered with the data about the number of toppings ordered, as displayed on the dot plot. Then answer this question.

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Homework Time

Activity 2

MLR7: Compare & Connect

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Work on the first 3 questions

(5-6 min)

Twenty-five sixth-grade students answered the question: “How many hours do you generally spend on homework each week?”

Why is this question a statistical question?

This dot plot shows the number of hours per week that these 25 students reported spending on homework.

Use the dot plot to answer the following questions. For each, show or explain your reasoning.

What percentage of the students reported spending 1 hour on homework each week?
What percentage of the students reported spending 4 or fewer hours on homework each week?

Would 6 hours per week be a good description of the number of hours this group of students spends on homework per week? What about 1 hour per week? Explain your reasoning.

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Share your responses with your partner and answer the last 2 questions together

What value do you think would be a good description of the homework time of the students in this group? Explain your reasoning.
Someone said, “In general, these students spend roughly the same number of hours doing homework.” Do you agree? Explain your reasoning.

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Let’s Talk About It

Where on the dot plot would you consider the center of the data? What is the value of that center?
Based on the dot plot, how would you describe the spread of the students’ homework time? Are the amounts of time they spend on homework alike or different?

Activity Synthesis

Ask a couple of students to share their thinking on what number of hours would be a good description of homework time for this group of students and why. Then, select a couple of other students to discuss how alike or different the lengths of homework time are.

Explain that sometimes it helps to describe a set of data generally, or to characterize it as a whole. One way to do that is by finding a value that describes the whole set reasonably well, or a value whose location can be considered the “center” of a distribution. Ask students:

“Where on the dot plot would you consider the center of the data? What is the value of that center?”

Another way to characterize a data set is by describing its “spread,” or the variability in the data points. The wider the spread (the more dispersed the data points are on a dot plot), the more variable or different they are. The narrower the spread (the more clustered together), the more alike they are. Ask students:

“Based on the dot plot, how would you describe the spread of the students’ homework time? Are the amounts of time they spend on homework alike or different?”

Tell students that we will continue to explore center and spread in upcoming lessons.

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Lesson Synthesis

What does the term “typical” mean? When someone wants to find out “a typical height of sixth-graders,” what is the information of interest?
How do tell what is typical from a dot plot such as this one? How might we describe the characteristics of this data set on dog weights?

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Today’s Goals

I can identify the spread and center of data from a dot plot.

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