In this activity, students brainstorm additional quantitative questions that could be asked about the world population.These questions will be used in a subsequent activity, where students will research and represent the ratios they gather in terms of the people in their class, as shown in "All 7.9 Billion of Us." Compile all of the questions into one document, removing inappropriate questions. 

Note that some questions in which students are interested may be challenging to research (for example, "how many people in the world have a car?"). If there is no chance to gather data beforehand, encourage students to make some simplifying assumptions about the data that they do find.

The goal of this discussion is to help students narrow down the questions to investigate and then to consider next steps, preparing them for the work in an upcoming activity.

Give each group a minute to identify 3–4 questions that they are most interested in investigating. Invite students to share the questions they identified.

Here are some questions for discussion:

• “Now that you have questions to investigate, how can you learn more about each topic?” (We can use the internet to research the answers.)
• “Are you expecting to find exact answers?” (No, any answer will be an estimate.)
• “What is a reasonable prediction for one of your questions?”

Consider compiling all of the questions into one document, removing inappropriate questions.
 

In this activity, students investigate answers to questions about the number of people in the world with certain characteristics. Then they find equivalent ratios that could describe these quantities if their class represented the world. Students can either use the questions previously selected by their group or choose 3–4 questions from a list compiled by the teacher.

Afterward, each group creates a graphical display to illustrate their findings for some or all of the questions. Encourage students to be creative with their displays. For example, if students are examining the question “How many people would live on each continent?” they might sketch the continents and place stick figures on the continents to represent the class. They might also draw a bar graph showing the same information in a different way.

As students work to express real-world ratios in terms of the number of students in their class and represent the information diagrammatically, they practice reasoning quantitatively and abstractly (MP2). As they translate quantities from a global scale to the scale of a class, they attend to precision (MP6).

Invite groups to share their displays. Consider asking students to do a Gallery Walk and encouraging them to consider these questions as they visit the displays:

• "Which of the findings surprise you?" (I was surprised that so many people are children.)
• “For which characteristics does our class actually represent the world?” (5 people in our class are vegetarian (20%) and about 19% of the world is vegetarian.)
• For which characteristics does our class not really represent the world? (25% of the world population do not have access to clean water but 100% of our class has access to clean water.)

Students may point out that having a small class limits the percentages that correspond to whole numbers of people. This can make deciding how many students in the class have a particular characteristic difficult. If this idea comes up, consider asking:

• What percentages correspond to whole numbers of students in the class? (For a class of 25 people, multiples of 4 up to 100)
• There are 1 billion people living in the Americas. That’s 13% of the world population. If our class were the world, how many students in our class would be from the Americas? (3 students would be 12%, and 4 would be 16%. So 3 students is as close as we can get.)