Lesson 1
Twoway Tables
Lesson Narrative
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.
Learning Goals
Teacher Facing
 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.
Student Facing
 Let’s look at categorical data.
Required Materials
Required Preparation
Print and cut the blackline master for the Info Gap lesson. Make one copy of the blackline master for every 2 students.
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.
CCSS Standards
Addressing
Glossary Entries

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.
has a cell phone does not have a cell phone 10–12 years old 25 35 13–15 years old 38 12 16–18 years old 52 8 
variable (statistics)
A characteristic of individuals in a population that can take on different values