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Lesson 1-1: Integer Addition & Subtraction

Scenario: Altitude Changes - Learn to calculate elevation changes using integer operations!

Duration: 50-65 minutesScenario: Altitude Changes

Learning Objectives

  • Use number line models to visualize integer addition and subtraction
  • Apply integer operations to solve altitude and temperature problems
  • Convert subtraction problems to addition using opposite numbers
  • Verify solutions using number line models

Altitude Change Scenario

The Problem

A mountain climber starts at an altitude of -120 meters (120 meters below sea level) and climbs up 350 meters. What is their final altitude?

Calculation: -120 + 350 = 230 meters

The climber ends up 230 meters above sea level.

Number Line Model

-200
-150
-100
-50
0
50
100
150
200
250
Start: -120m
→
End: 230m

Visual Tip: Start at -120, move right 350 units to reach 230. The arrow shows the direction and distance of movement.

Subtraction as Addition

Temperature Example

The temperature is -5°C. It drops 3 degrees. What is the new temperature?

Method 1: Direct Subtraction

-5 - 3 = -8°C

Method 2: Addition of Opposite

-5 + (-3) = -8°C

Key Rule

Subtracting a positive number is the same as adding a negative number:

a - b = a + (-b)

Practice Problems

Problem 1

Calculate: 5 - (-7) = ?

Your solution:

5 - (-7) = 5 + 7 =

Problem 2

Calculate: -9 + (-6) = ?

Your solution:

-9 + (-6) =

Problem 3: Real-World Application

A submarine is at -200 meters depth. It rises 150 meters, then dives 80 meters. What is its final depth?

Your calculation:

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