~ 5.3 ~
Changing Elevation
Learning Targets
I understand how to add positive and negative numbers in general.
Notes
The opposite of a number is the same distance from 0 but on the other side of 0.
The opposite of -9 is 9. When we add opposites, we always get 0. This diagram shows that 9 + -9 = 0.
When we add two numbers with the same sign, the arrows that represent them point in the same direction. When we put the arrows tip to tail, we see the sum has the same sign.
To find the sum, we add the magnitudes and give it the correct sign. For example, (-5) + (-4) = -(5+4).
On the other hand, when we add two numbers with different signs, we subtract their magnitudes (because the arrows point in the opposite direction) and give it the sign of the number with the larger magnitude. For example, (-5) + 12 = + (12 - 5).
Activities
3.2 Cliffs and Caves
Explore the applet and then answer the questions below.
A mountaineer is climbing on a cliff. She is 200 feet above the ground. If she climbs up, this will be a positive change. If she climbs down, this will be a negative change.
Complete the table.
Select three rows from the table and draw a number line diagram for each. Include the starting elevation, change, and final elevation on each diagram.
A spelunker is down in a cave next to the cliff. If she climbs down deeper into the cave, this will be a negative change. If she climbs up, whether inside the cave or out of the cave and up the cliff, this will be a positive change.
Complete the table.
Select three rows from the table and draw a number line diagram for each. Include the starting elevation, change, and final elevation on each diagram.
Complete the table and draw a number line diagram to represent each row in this table.
3.3 Adding Rational Numbers
Find the sums.
-35 + (30 + 5)
-0.15 + (-0.85) + 12.5
½ + (-¾)
Summary
Assignment
Check Google Classroom!