Lesson 2Changing Temperatures
Learning Goal
Let’s add signed numbers.
Learning Targets
I can use a number line to add positive and negative numbers.
Warm Up: Which One Doesn’t Belong: Arrows
Problem 1
Which pair of arrows doesn’t belong?
Activity 1: Warmer and Colder
Problem 1
Complete the table and draw a number line diagram for each situation.
start ( | change ( | final ( | addition equation | |
---|---|---|---|---|
a | 10 degrees warmer | |||
b | 5 degrees colder | |||
c | 30 degrees colder | |||
d | 40 degrees colder | |||
e | 50 degrees colder |
Problem 2
Complete the table and draw a number line diagram for each situation.
start ( | change ( | final ( | addition equation | |
---|---|---|---|---|
a | 30 degrees warmer | |||
b | 35 degrees warmer | |||
c | 15 degrees warmer | |||
d | 15 degrees colder |
Are you ready for more?
Problem 1
For the numbers
Activity 2: Winter Temperatures
Problem 1
One winter day, the temperature in Houston is
In Orlando, it is
warmer than it is in Houston. In Salt Lake City, it is
colder than it is in Houston. In Minneapolis, it is
colder than it is in Houston. In Fairbanks, it is
colder than it is in Minneapolis. Use the thermometer applet to verify your answers and explore your own scenarios.
Print Version
One winter day, the temperature in Houston is
In Orlando, it is
warmer than it is in Houston. In Salt Lake City, it is
colder than it is in Houston. In Minneapolis, it is
colder than it is in Houston. In Fairbanks, it is
colder than it is in Minneapolis. Write an addition equation that represents the relationship between the temperature in Houston and the temperature in Fairbanks.
Lesson Summary
If it is
If the temperature decreases by
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
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