The mathematical purpose of this lesson is to create and interpret twoway tables. Twoway tables are used to organize data on two categorical variables. Students encounter the term categorical variable, which is a variable that represents data which can be divided into groups or categories. In statistics, a variable is a characteristic that can take on different values. In eighth grade, students had the opportunity to use twoway tables. The first few tasks incorporate some embedded review. In later lessons, students create and interpret twoway tables showing relative frequencies. When students answer questions about some data, they are making use of the structure of the tables (MP7) to organize and understand the information from descriptions of data. In the Information Gap activity, students must make sense of problems and persevere in solving them (MP1) and attend to the precision of their language (MP6) to ask appropriate questions of their peers.
Lesson overview
 1.1 Warmup: Utensils and Paper Preferences (10 minutes)

1.2 Activity: Fruit Fly Mutations (10 minutes)
 Includes "Are you Ready for More?" extension problem
 1.3 Activity: Info Gap: Running to the Dentist (10 minutes)
 Lesson Synthesis
 1.4 Cooldown: Oh, Deer (5 minutes)
Learning goals:
 Calculate the total number of individuals in a group given a twoway table.
 Create twoway tables based on information given in everyday language.
 Interpret values (orally and in writing) in twoway tables.
Learning goals (student facing):
 Let’s look at categorical data.
Learning targets (student facing):
 I can calculate missing values in a twoway table.
 I can create a twoway table for categorical data given information in everyday language.
 I can describe what the values in a twoway table mean in everyday language.
Required Materials
 Preprinted slips, cut from copies of the blackline master
Required Preparation
 Print and cut the blackline master for the Info Gap activity. Make one copy of the blackline master for every 2 students.
Glossary:
 categorical variable  A variable that takes on values which can be divided into groups or categories. For example, color is a categorical variable which can take on the values, red, blue, green, etc.
 twoway table  A way of organizing data from two categorical variables in order to investigate the association between them.
 variable (statistics)  A characteristic of individuals in a population that can take on different values
 Access the complete Algebra 1 glossary.
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