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Unit 6 - Lesson 9 - Grade 8: Illustrative Mathematics

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8 Questions
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Grade 8 Unit 6
Lesson 9: Looking for Associations
CC BY 2021 Illustrative Mathematics®
Grade 8 Unit 6
Lesson 9: Looking for Associations
CC BY 2021 Illustrative Mathematics®
Lesson: Looking for Associations

Notice and Wonder: Bar Association (Warm Up)

1.

What do you notice? What do you wonder?


Card Sort: Matching Representations

Your teacher will hand out some cards.

Some cards show two-way tables like this:



Some cards show bar graphs like this:



Some cards show segmented bar graphs like this:

The bar graphs and segmented bar graphs have their labels removed.
  • Put all the cards that describe the same situation in the same group.
2.

One of the groups does not have a two-way table. Make a two-way table for the situation described by the graphs in the group.

  • Label the bar graphs and segmented bar graphs so that the categories represented by each bar are indicated.
3.

Describe in your own words the kind of information shown by a segmented bar graph.

Building Another Type of Two-Way Table

Here is a two-way table that shows data about cell phone usage among children aged 10 to 18.

4.

Complete the table. In each row, the entries for “has cell phone” and “does not have cell phone” should have the total 100%. Round entries to the nearest percentage point.


This is still a two-way table. Instead of showing frequency, this table shows relative frequency.

5.

Two-way tables that show relative frequencies often don’t include a “total” row at the bottom. Why?

6.

Is there an association between age and cell phone use? How does the two-way table of relative frequencies help to illustrate this?

Cool Down: Guitar and Golf

Guitar and Golf

7.

In a class of 25 students, some students play a sport, some play a musical instrument, some do both, some do neither. Complete the two-way table to show data that might come from this class.

8.

Using the entries from the previous table, complete this table so that it shows relative frequencies. Round entries to the nearest percentage point.