The purpose of this activity is to build students’ intuition for 1 kilometer. Previously, students used centimeter grid paper and counted 100 units to build a length of 1 meter. Since building a kilometer is impractical, here students relate 1 kilometer to the length of other objects that may be more familiar. For instance, if an Olympic-size pool is 50 meters long, the length of 2 pools is 100 meters and the length of 20 pools is 1,000 meters or 1 kilometer.

The blackline master shows copies of a few objects: a soccer field, the Statue of Liberty, an Olympic-size pool, or a basketball court. Students work with their group to cut out these images and use the copies of each object to reason about the length of 1 kilometer.

• Select students to share their work on how the four objects compare to 1 kilometer.
• For each response, ask: “¿Cómo supiste cuántos de ese objeto se necesitarían para completar una longitud de 1 kilómetro?” // “How did you know how many of that object it would take to make a length of 1 kilometer?” (For the soccer field:
  • I added 110 repeatedly until it reached 1,000.
  • I know that 5 soccer fields make 550, and I thought about how many of that length would make 1,000.
  • I tried multiplying 110 feet by different numbers to reach 1,000.
  • I thought about how many 110s would go into 1,000.)
• Invite students to share their responses to the last problem.
• Consider giving or displaying for students a map showing one or more points that are 100 meters from school, and asking them to identify a place that is 1 kilometer away from the school.
• Emphasize that 1 kilometer is 1,000 times as long as 1 meter. If we use 1 meter as a unit of measurement, we’ll need 1,000 of it to make 1 kilometer. Explain that kilo means “thousand.”

The purpose of this activity is for students to convert measurements from kilometers into meters and to reason the other way around. When the given measurement is a whole number of kilometers, students likely will multiply the whole number by 1,000 to find its equivalent in meters. For kilometer, they likely will reason that half of 1,000 is 500, or that 1,000 divided by 2 is 500. Students are not expected to reason multiplicatively or to know that is 500. The Lesson Synthesis focuses on discussing Andre's reasoning from the task.

• Display the table.
• Invite selected students to share their reasoning on how they converted each whole-number measurement. Start with students who reasoned by counting and end with those who reasoned multiplicatively.
• Discuss how students found the number of meters in  kilometer and kilometers. Record their reasoning.