Friday
Friday: Signed Numbers All Around
Rocket presses the elevator button marked -1 at the library. "Below ground. One floor under the lobby."
"Zero is the lobby," says Raven. "What do you notice about the buttons above it?"
"Positive floors," Rocket says. "And the car park is negative. Same as the thermometer, same as the par game."
Nova hovers beside the panel. "One rule for all of them," she says. "Opposite directions, opposite signs, 0 in the middle."
"And the farther from 0, the bigger the absolute value," Raven adds, "whether it is up or down."
Rocket grins. "So next week, when the temperature goes from -4 up to 2, how far did it climb?"
Nova hums. "Six. But next week you learn to add and subtract your way there."
Signed numbers in everyday life
Elevators: floors below the lobby are negative. Floor -2 is lower than floor -1, but it is farther from the lobby.
Scores: a game where you can lose points goes below 0. A score of -3 is less than a score of 1.
Thermometers: -3 degrees is warmer than -7 degrees. Write it as -3 > -7.
Timelines: a countdown before a launch uses negative seconds, and 0 is the moment of launch.
Order and absolute value are different questions
"Which is less?" is about order: -8 < -3, because -8 is farther left.
"Which is farther from 0?" is about absolute value: |-8| = 8 and |-3| = 3, so -8 is farther.
A temperature lower than -5 is colder than -5, and more than 5 degrees from freezing. Both statements are true at once.
- Read the question.
- Tap your answer.
- Read the question.
- Tap your answer.
Point P is at (-2, 5). Which quadrant is it in?| Week review | True or false? |
|---|---|
| -3 > -7 | ? |
| |-8| is less than |-3|. | ? |
| The opposite of 0 is 0. | ? |
| The point (-2, -5) is in Quadrant III. | ? |
| Floor -2 is higher than floor -1. | ? |
- ?We wrote numbers above and below zero and found their opposites.
- ?We put signed numbers in order and measured their distance from 0.
- ?We kept a weather log and played the par game on one tall number line.
- ?We drew the Field Day map on four quadrants and found distances between stations.
Write that number's absolute value and its opposite.
A whole week below zero and back. Tomorrow is Data Day: a treasure map on four quadrants with your family.