Page 100 - IM_Algebra1_FL Print Sample.pdf

• “How does this activity relate to prior work with relative frequency tables?” (We did not make the table here but we had to use the values that we could have found by creating relative frequency tables. For this activity, you would have needed three relative frequency tables.)
• “For the second question, did you use the row totals or the column totals?” (The row totals.)
• “The overall total was 300, how many people would you expect to prefer cake and be left handed if the overall total was 600? How does this connect to the concept of relative frequency?” (20. It is connected to relative frequency because 10 out of 300 is the same ratio as 20 out of 600.)
3.2 Associations in Categorical Data
15 minutes
The mathematical purpose of this activity is to look for associations in categorical data. Monitor for students who use the term association in their explanations. Identify students who struggle with knowing whether to compare frequencies in the columns or the rows, and for students who do not know how to nd relative frequencies.
Launch
Arrange students in groups of 2. After students have had a chance to work through the rst problem about coral health, pause the work to discuss what students noticed about possible associations. Ensure that the discussion concludes that when the column (or row) percentages are similar (like with the silicon dioxide concentration), there is probably no association between the di erent variables. When the percentages are not close (like with the nitrate concentration), there is likely an association between the variables.
Give students quiet think time to work through the remaining problems. Follow with a whole-class discussion.
Student Task Statement
1. The two-way table displays data about 55 di erent locations. Scientists have a list of possible chemicals that may in uence the health of the coral. They rst look at how nitrate concentration might be related to coral health. The table displays the health of the coral (healthy or unhealthy) and nitrate concentration (low or high).
low nitrate concentration
high nitrate concentration
total
healthy
20
5
25
unhealthy
8
22
30
total
28
27
55
Unit 3
Lesson 3: Associations in Categorical Data 33