🎓 Mini-Lesson: Understanding Negative Numbers
What are Negative Numbers?
Negative numbers are numbers less than zero. They're written with a minus sign (-) in front. We see them in real life with temperatures below freezing, depths below sea level, or money owed!
Temperature Scale (°C)
20°C
10°C
0°C
-10°C
-20°C
Above 0°C is positive (warm), below 0°C is negative (cold)!
🔑 Rules for Adding and Subtracting:
| Operation | What to do | Example |
| Adding a positive | Move RIGHT on the number line | -3 + 5 = 2 |
| Adding a negative | Move LEFT on the number line | 4 + (-6) = -2 |
| Subtracting a positive | Move LEFT on the number line | 2 - 5 = -3 |
| Subtracting a negative | Move RIGHT (two minuses make a plus!) | -2 - (-4) = 2 |
Example 1: -5 + 8 = ?
Start at -5, then move 8 steps to the RIGHT
-5 → -4 → -3 → -2 → -1 → 0 → 1 → 2 → 3
Answer: 3
Start at -5, then move 8 steps to the RIGHT
-5 → -4 → -3 → -2 → -1 → 0 → 1 → 2 → 3
Answer: 3
Example 2: 3 - 7 = ?
Start at 3, then move 7 steps to the LEFT
3 → 2 → 1 → 0 → -1 → -2 → -3 → -4
Answer: -4
Start at 3, then move 7 steps to the LEFT
3 → 2 → 1 → 0 → -1 → -2 → -3 → -4
Answer: -4
Example 3: -6 + (-2) = ?
Start at -6, adding a negative means move 2 steps to the LEFT
-6 → -7 → -8
Answer: -8
Start at -6, adding a negative means move 2 steps to the LEFT
-6 → -7 → -8
Answer: -8
Example 4: -3 - (-5) = ?
Two minuses make a plus! So this is really -3 + 5
Start at -3, move 5 steps to the RIGHT
-3 → -2 → -1 → 0 → 1 → 2
Answer: 2
Two minuses make a plus! So this is really -3 + 5
Start at -3, move 5 steps to the RIGHT
-3 → -2 → -1 → 0 → 1 → 2
Answer: 2
💡 Remember: Think of a number line or temperature scale to help you!
✏️ Practice Questions
Calculate the answers. Don't forget to include the minus sign for negative answers!