To enrich or extend the lesson, display the Challenge Problem: Your Town in Relation to the World in the Teacher Guide. Write the population of your town and the population of the world (about 7 billion) on the display.
- How many towns of our size would it take to equal the population of the world? (Answers will vary.)
- What math strategies could we use to find the solution? (Possible responses include MPE2, MPE3, and MPE5.)
Have students work in small groups to explore a solution to this problem. Bring them back together to share their thinking.
- What strategies did you use to find how many towns of our size it would take to equal the population of the world? (Possible response: I tried to make a number line that started at our town's population and used the base-ten hopper to hop that number until it reached 7 billion, then counted the number of hops but the number was too big to draw on a number line.
If our town is 500,000, two of our towns make up one million. Since there are 1,000 millions in one billion, it would take 2,000 towns to cover one billion people. There are 7 billion people in the world so 7 × 2,000 = 14,000 towns.
- What number sentences could you write to help figure this out? (Possible responses: 500,000 + 500,000 = 500,000 × 2 = 1,000,000 1,000,000 × 1000 = 1,000,000,000 2 × 1000 = 2,000 towns in 1,000,000,000 2,000 × 7 = 14 thousand towns in 7 billion)
Steps to solve the Challenge Problem: Your Town in Relation to the World:
Find how many towns of your size are in a million. Multiply this number by 1000 to find how many towns are in one billion. Multiply this by 7 to find how many towns are in 7 billion.
