Predicting Populations

5 min

Narrative

The purpose of this warm-up is to familiarize students with data in a context that they will be using in a later activity. While students may notice and wonder many things about these data, estimates of average rate of change and curiosity about models for the populations are the important discussion points.

This Warm-up prompts students to make sense of a problem before solving it, by familiarizing themselves with a context and the mathematics that might be involved (MP1). 

Launch

Arrange students in groups of 2. Display the table for all to see. Ask students to think of at least one thing they notice and at least one thing they wonder about. Give students 1 minute of quiet think time, and then 1 minute to discuss the things they notice and wonder with their partner.

Student Task

Here are the populations of three cities during different years.

What do you notice? What do you wonder?

City 1950 1960 1970 1980 1990 2000
Paris 6,300,000 7,400,000 8,200,000 8,700,000 9,300,000 9,700,000
Austin 132,000 187,000 254,000 346,000 466,000 657,000
Chicago 3,600,000 3,550,000 3,400,000 3,000,000 2,800,000 2,900,000


Sample Response

Students may notice:

  • The population of Paris is growing more slowly as time goes by.
  • The population of Austin is growing more and more rapidly.
  • The population of Chicago decreased for many years but started to increase again near the year 2000.

Students may wonder:

  • Why is Austin growing so quickly?
  • Why did the population in Chicago decrease?
  • Will Austin ever have as many people as Chicago (or Paris)?
Activity Synthesis (Teacher Notes)

Ask students to share the things they noticed and wondered about. Record and display, for all to see, their responses without editing or commentary. If possible, record the relevant reasoning on or near the table. Next, ask students, “Is there anything on this list that you are wondering about now?” Encourage students to observe what is on display and to respectfully ask for clarification, point out contradicting information, or voice any disagreement.

If a general description of the trends in population and possible models for population do not come up during the conversation, ask students to discuss this idea.

For example:

  • Paris has been growing steadily but not at a constant rate.
  • Austin has been growing very rapidly.
  • Chicago's population has decreased, at a variable rate, but it increased in the decade from 1990 to 2000.
Standards
Building Toward
  • F-LE.1·Distinguish between situations that can be modeled with linear functions and with exponential functions.
  • F-LE.1·Distinguish between situations that can be modeled with linear functions and with exponential functions.
  • F-LE.1·Distinguish between situations that can be modeled with linear functions and with exponential functions.
  • HSF-LE.A.1·Distinguish between situations that can be modeled with linear functions and with exponential functions.

25 min

20 min