Changing Elevation

5 min

Narrative

In this Warm-up, students think about opposite values and actions in different real-world situations. Students represent adding a number and its opposite on a number line. This will be useful when students think about opposite numbers and situations in following activities.

Launch

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

Student Task

  1. Draw arrows on a number line to represent these situations:​

    1. The temperature was -5 degrees. Then the temperature rose 5 degrees.

      A number line with 21 evenly spaced tick marks. 

    2. A climber was 30 feet above sea level. Then she descended 30 feet.

      A number line with 21 evenly spaced tick marks. 

  2. What’s the opposite?

    1. running 150 feet east
    2. jumping down 10 steps
    3. pouring 8 gallons into a fish tank

Sample Response

  1. Sample responses:

    1. running 150 feet west

    2. jumping up 10 steps

    3. pouring 8 gallons out of a fish tank

Synthesis

The goal of this discussion is for students to come up with many different concrete examples of opposites. Begin by inviting a few students to share their responses. Then ask students to describe additional pairs of situations and numbers that are opposites. For example, students might say that 5 hours later is the opposite of 5 hours earlier or that turning 90 degrees clockwise is the opposite of turning 90 degrees counterclockwise.

Standards
Addressing
  • 7.NS.1.a·Describe situations in which opposite quantities combine to make 0. <em>For example, a hydrogen atom has 0 charge because its two constituents are oppositely charged.</em>
  • 7.NS.A.1.a·Describe situations in which opposite quantities combine to make 0. <span>For example, a hydrogen atom has 0 charge because its two constituents are oppositely charged.</span>

15 min

10 min

10 min