# Lesson 2

If Our Class Were the World

### Lesson Narrative

This lesson is optional. In this lesson, students look at ratios of different populations in the world and determine what their class would be like if its ratios were equivalent (MP1, MP2). In the process, they again work with percentages that are not whole numbers, using knowledge gained in a previous unit. Moreover, the ratios will be “close” to being equivalent because the exact world population is not known and all populations need to be whole numbers (MP6). The activities in this lesson could take anywhere from one to four days, depending on how much time is available and how far the class takes it. Earlier activities are needed for later ones in this lesson. A variant on this activity involves developing, administering, and analyzing a survey: If the school were our class. Students brainstorm some questions they would like to know about the students in their school. Questions might include:

• How many people in the school play an instrument?
• How many people in the school eat school lunches?
• How many people in the school ride the bus to school?
• How many people in the school have a cell phone?
• How many people in the school plan to attend a four-year college or university?
• How many people in the school were born outside of this state?
• How many people in the school have traveled outside of this country?

As with all lessons in this unit, all related standards have been addressed in prior units; this lesson provides an optional opportunity to go more deeply and make connections between domains.

### Learning Goals

Teacher Facing

• Apply reasoning about percentages and equivalent ratios to analyze and approximate characteristics of the world’s population.
• Generate (orally and in writing) mathematical questions about the world’s population, e.g., “How many people . . . ?”
• Present (using words and other representations) a comparison that uses the number of students in the class to represent the proportion of the world’s population with a particular characteristic.

### Student Facing

Let’s use math to better understand our world.

### Required Preparation

Internet-enabled devices are only necessary if students will conduct research to find quantities that they need to know. As an alternative, you can supply the information when they ask for it.

Tools for creating a visual display are only needed if you would like students to present their work in an organized way and have the option of conducting a gallery walk.