~ 5.1 ~

Interpreting Negative Numbers

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Unit 5

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Learning Targets

I can compare rational numbers.
I can use rational numbers to describe temperature and elevation.

Notes

We can use positive and negative numbers to represent temperature and elevation.

When numbers represent temperatures, positive numbers indicate temperatures that are warmer than zero and negative numbers indicate temperatures that are colder than zero. This thermometer shows a temperature of -1 degree Celsius, which we write -1∘C.

When numbers represent elevations, positive numbers indicate positions above sea level and negative numbers indicate positions below sea level.

We can see the order of signed numbers on a number line, which are usually drawn horizontally. Negatives numbers are to the left of zero.

A number is always less than numbers to its right. So -7 < -3.

We use absolute value to describe how far a number is from 0. The numbers 15 and -15 are both 15 units from 0, so |15| = 15 and |-15| = 15. We call 15 and -15 opposites. They are on opposite sides of 0 on the number line, but the same distance from 0.

Missing numbers on the number linePractice more challenging problems where you identify positive and negative integers on a number line that doesn't have zero labeled.

Order rational numbersPractice comparing decimals, percents, fractions, and mixed numbers.

Activities

1.2 Fractions of a Degree

Degrees Celsius is a way of measuring temperature, like degrees Fahrenheit.

0^o Celsius is based on the freezing point of water.

0^o Fahrenheit is based on the freezing point of saltwater.

These temperatures were chosen by people, and there’s no reason they had to be this way.

What temperature is shown on each thermometer?
Which thermometer shows the highest temperature?
Which thermometer shows the lowest temperature?
Suppose the temperature outside is -4∘C. Is that colder or warmer than the coldest temperature shown? How do you know?

A B C D

1.3 Seagulls Soar, Sharks Swim

Here is a picture of some sea animals. The number line on the left shows the vertical position of each animal above or below sea level, in meters.

How far above or below sea level is each animal? Measure to their eye level.
A mobula ray is 3 meters above the surface of the ocean. How does its distance from the surface of the ocean compare to the vertical distance from the eyes of:
- The jumping dolphin?
- The flying seagull?
- The octopus?
An albatross is 5 meters above the surface of the ocean. How does its distance from the surface compare to the vertical distance from the eyes of:
- The jumping dolphin?
- The flying seagull?
- The octopus?
A clownfish is 2 meters below the surface of the ocean. How does its distance from the surface compare to the vertical distance from the eyes of:
- The jumping dolphin?
- The flying seagull?
- The octopus?
The vertical distance of a new dolphin from the dolphin in the picture is 3 meters. What is its distance from the surface of the ocean?

Add to Your Notes

Negative numbers can be used to represent quantities below a chosen zero point.
Negative numbers can be ordered to the left side of zero on a horizontal number line.
Absolute value, or magnitude, describes how far away from zero a value is.

Summary

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