Unit 7, Lesson 1
Positive and Negative Numbers
Accelerated 6
1.1
Warm-up
What do you notice? What do you wonder?
1.3
Activity
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Here are five thermometers. The first four thermometers show temperatures in degrees Celsius . Write the temperatures in the blanks.
Five vertical thermometers, a through e. Thermometer a is shaded up to 1. Thermometer b is shaded up to 2. Thermometer c is shaded up to the halfway point between 3 and 4. Thermometer d is shaded to the halway point between negative 1 and 0. Thermometer has tick marks labeled negative 20, blank, blank, negative 5, blank, blank, ten, blank, blank, 25. - The last thermometer is missing some numbers. Write them in the boxes.
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Elena says that the thermometer shown here reads because the line is above . Jada says that it is . Do you agree with either of them? Explain your reasoning.
1.4
Activity
Here is a picture of some sea animals. The number line on the left shows the vertical position, in meters, of each animal above or below sea level.
- 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 vertical position compare to the height or depth of:
- An albatross is 5 meters above the surface of the ocean. How does its vertical position compare to the height or depth of:
- A clownfish is 2 meters below the surface of the ocean. How does its vertical position compare to the height or depth of:
- The vertical distance between a new dolphin and the dolphin in the picture is 3 meters. What is the new dolphin’s distance from the surface of the ocean?
A graph. Vertical axis is labeled vertical position, in meters. 5 tick marks. Scale from negative 15 to 15, by 5s. Horizontal axis has no label or scale. Seagull is at 10. Dolphin is at 3. Penguin is at 0. Shark is at negative 3. Fish is at negative 7. Octopus is at negative 10.
The jumping dolphin?
The flying seagull?
The octopus?
The jumping dolphin?
The flying seagull?
The octopus?
The jumping dolphin?
The flying seagull?
The octopus?
Student Lesson Summary
Positive numbers are numbers that are greater than zero. Negative numbers are numbers that are less than zero. The meaning of a negative number in a context depends on the meaning of zero in that context.
For example, if we measure temperatures in degrees Celsius, 0 degrees Celsius corresponds to the temperature at which water freezes.
In this context, positive temperatures are warmer than the freezing point, and negative temperatures are colder than the freezing point. A temperature of -6 degrees Celsius means that it is 6 degrees away from 0 and that it is less than 0. This thermometer shows a temperature of -6 degrees Celsius.
If the temperature rises a few degrees and gets very close to 0 degrees, without reaching it, the temperature is still a negative number.
Another example is elevation, which is a distance above or below sea level. An elevation of 0 refers to sea level. Positive elevations are higher than sea level, and negative elevations are lower than sea level.
In this context, a bird flying in the sky would have a positive elevation because it is higher than sea level. An octopus or a shark would have a negative elevation because it is swimming below sea level.
A negative number is a number that is less than 0.
A positive number is a number that is greater than 0.