Negative Rates

5 min

Narrative

In this Warm-up, students review "per" language by considering situations that deal with constant rates. This will be useful in following activities when students perform calculations with signed numbers involving rates.

Launch

Arrange students in groups of 2. Give students 1 minute of quiet work time followed by 1 minute of partner discussion. Then follow with a whole-class discussion.

Student Task

  1. If you fold 5 shirts per minute for 8 minutes, how many shirts will you fold?
  2. If you hear 9 new songs per day for 3 days, how many new songs will you hear?
  3. If you run 15 laps per practice, how many practices will it take you to run 30 laps?

Sample Response

  1. 40 shirts
  2. 27 songs
  3. 2 practices

Synthesis

For each question, invite a student to share their response and reasoning. Resolve any disagreements that come up. Remind students that whenever we see the word "per," it means "for every 1."

Standards
Addressing
  • 7.RP.A·Analyze proportional relationships and use them to solve real-world and mathematical problems.
  • 7.RP.A·Analyze proportional relationships and use them to solve real-world and mathematical problems.
Building Toward
  • 7.NS.3·Solve real-world and mathematical problems involving the four operations with rational numbers.
  • 7.NS.A.3·Solve real-world and mathematical problems involving the four operations with rational numbers.<span>Computations with rational numbers extend the rules for manipulating fractions to complex fractions.</span>

15 min

15 min