Embedded Files
Learning Targets
- I can use a number line to add positive and negative numbers.
Notes
Notes
If it is 42∘ outside and the temperature increases by 7∘, then we can add the initial temperature and the change in temperature to find the final temperature.
42+7=49
If the temperature decreases by 7∘, we can either subtract 42−7 to find the final temperature, or we can think of the change as -7∘. Again, we can add to find the final temperature.
42+(-7)=35
In general, we can represent a change in temperature with a positive number if it increases and a negative number if it decreases. Then we can find the final temperature by adding the initial temperature and the change. If it is 3∘ and the temperature decreases by 7∘, then we can add to find the final temperature.
3+(-7)=-4
We can represent signed numbers with arrows on a number line. We can represent positive numbers with arrows that start at 0 and points to the right. For example, this arrow represents +10 because it is 10 units long and it points to the right.
We can represent negative numbers with arrows that start at 0 and point to the left. For example, this arrow represents -4 because it is 4 units long and it points to the left.
To represent addition, we put the arrows “tip to tail.” So this diagram represents
And this represents 3+(-5):
Activities
Activities
2.2 Warmer and Colder
2.2 Warmer and Colder
1. Complete the table and draw a number line diagram for each situation.
2. Complete the table and draw a number line diagram for each situation.
2.3 Winter Temperatures
2.3 Winter Temperatures
These are the locations you'll be looking at in this activity. In the northern hemisphere, it tends to be colder the father north you are located.
- One winter day, the temperature in Houston is 8∘ Celsius. Find the temperatures in these other cities. Explain or show your reasoning.
- In Orlando, it is 10∘ warmer than it is in Houston.
- In Salt Lake City, it is 8∘ colder than it is in Houston.
- In Minneapolis, it is 20∘ colder than it is in Houston.
- In Fairbanks, it is 10∘ colder than it is in Minneapolis. What is the temperature in Fairbanks?
- Use the thermometer applet to verify your answers and explore your own scenarios.
Add to Your Notes
Add to Your Notes
- We can represent a decrease as adding a negative number.
- We can represent addition on a number line with two arrows, the second arrow starting where the first arrow ends.
- We can represent a negative addend on a number line as an arrow pointing to the left.
Summary
Summary
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