### Lesson Summary

### Overview

This *Cyberchase* activity first addresses a common misconception: starting measurement from 1 instead of 0. Then, it introduces negative numbers by extending a number line beyond 0 in the negative (left) direction. It is motivated by the CyberSquad's mission to find the captured Cyberchase Council on a particular floor of a tall building.

### Grade Level:

4-8

### Suggested Time

1 hour

### Media Resources

Importance of the Origin QuickTime Video

Inventing Negative Numbers QuickTime Video

### Materials

Handout: Elevator Number Line

Asessment: Level A

Assessment: Level B

Answer Key

### The Lesson

### Part I: Learning Activity

1. Tell the students that they will watch a video, but before showing video clip 1, read them the following: "The CyberSquad is searching for the Cyberchase Council, who are being held captive by Hacker in a tall building. The doors to the stairs are locked and the elevator does not work. So they use a window washer elevator to get to the 18th floor, but they make 1 mistake. Can you find the mistake?"

2. Show Importance of the Origin QuickTime Video (Note: Do not tell the students the title of the segment).

3. Pause the clip when Digit, the Cyberbird, lands in a mud tub on the wrong floor.

4. Ask the students if they saw the mistake, which involved starting their count at 1 instead of 0 for the ground floor, and have them explain the mistake.

5. Play the remaining part of the video segment.

6. Distribute the Handout: Elevator Number Line.

7. Ask students to complete Part 1, in which they move up and down the external elevator according to MotherBoard's instructions.

8. Tell the students that they will now watch another video segment from the same episode (Note: Do not mention the title of the sement to the students).

9. Show Inventing Negative Numbers QuickTime Video.

10. Discuss with the students their results for Part 1 of the handout, and compare their results with the results in the video segment.

11. Ask the students to complete Part 2 of the handout, which asks them to compare number size involving negative numbers.

### Part II: Assessment

Asessment: Level A (proficiency): Students are asked to complete simple change of directions problems using a number line, and to compare pairs of integers to indicate whether the first is less than or greater than the second number in each pair.

Assessment: Level B (above proficiency): Students are asked to complete harder change of directions problems, and to compare pairs of larger integers to indicate whether the first is less than or greater than the second number in each pair.