Operations on Integers

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Subject: Mathematics

Semester: 1

Period: 1

Week: 5

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School Name:
Teacher’s Name:
Subject: Mathematics
Grade Level: Grade 6
Date: Week 5
Lesson Duration: 45 minutes
Week & Period: Week 5, Period 1
Topic: Operations on Integers
Sub-topic: Addition, Subtraction, Multiplication, Division

Learning Objectives
By the end of the lesson, students should be able to:
Add, subtract, multiply, and divide integers
Use integers in word problems
Use number line for operations

Previous Knowledge
Students already know positive and negative numbers and zero.

Instructional Materials
Mathematics textbook for Grade 6, number lines, counters, flashcards.

Lesson Development – ABC Model
A – Anticipation (Warm-up / Starter)
Time: 5–10 minutes
Teacher asks: “If the temperature is -3°C and rises by 5°C, what is the new temperature?”

B – Building Knowledge (Main Lesson Body)

Time: 25–30 minutes

Definition: Integers

• Integers are whole numbers and their negatives, including zero.
• Examples: {..., -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, ...}.
• Integers are used in real life to represent loss and gain, below/above sea level, cold/hot temperature, money debit/credit, and elevations.

 

Rules for Operations with Integers

1. Addition of Integers
   • If signs are the same: add numbers, keep the sign.
     • Example: (+3) + (+2) = +5
     • Example: (-4) + (-6) = -10
   • If signs are different: subtract, take sign of the larger absolute value.
     • Example: (+7) + (-5) = +2
     • Example: (-9) + (+3) = -6

2. Subtraction of Integers
   • Change subtraction into addition of the opposite.
   • Example: (+5) - (+3) = (+5) + (-3) = +2
   • Example: (-2) - (+4) = (-2) + (-4) = -6
   • Example: (+6) - (-3) = (+6) + (+3) = +9
3. Multiplication of Integers
   • Same signs → Positive product.
   • Different signs → Negative product.
   • Examples:
     • (+3) × (+4) = +12
     • (-5) × (-2) = +10
     • (+7) × (-3) = -21

4. Division of Integers
   • Same signs → Positive quotient.
   • Different signs → Negative quotient.
   • Examples:
     • (+8) ÷ (+2) = +4
     • (-12) ÷ (-3) = +4
     • (-20) ÷ (+5) = -4

 

Use of Number Line

• The number line helps to visualize addition and subtraction of integers.
• Example: To calculate (+3) + (-2), start at 3, move 2 steps left → land on 1.
• Example: To calculate (-5) + (+7), start at -5, move 7 steps right → land on 2.

 

Learners’ Activities (Expanded)

1. Individual Practice:
   • Learners solve integer addition and subtraction on a number line.
2. Group Activity:
   • Groups multiply and divide integers using prepared flash cards (one with numbers, one with operation signs).
3. Real-Life Word Problems:
   • Temperature: If it is -3°C in the morning and the temperature rises by 6°C, what is the new temperature? (+3°C).
   • Money: A person owes L$50 (−50) and pays L$20 (+20). What is the balance? (−30).
   • Elevation: A diver is at -15m below sea level and rises 10m. What is the new position? (−5m).

 

Assessment Checks

1. Teacher asks learners to calculate:
   • (−5) + (+7) = ?
   • (−9) ÷ 3 = ?
   • (+4) × (−2) = ?
2. Quick Quiz:
   • (+8) − (−3) = ?
   • (−12) + (−7) = ?
   • (−16) ÷ (−4) = ?
3. True/False:
   • The product of two negative integers is negative. (False).
   • Subtracting an integer is the same as adding its opposite. (True).

 

Notes (Expanded & Detailed)

• Addition:
• Same signs → add and keep sign.
• Different signs → subtract, take sign of larger absolute value.
• Subtraction: Always convert into addition of the opposite.
• Multiplication/Division:
• Same sign → Positive result.
• Different signs → Negative result.
• Operations on integers are useful in daily life — handling temperatures, money, debts, elevations, and business profit/loss.

C – Consolidation (Conclusion & Assessment)
Time: 5–10 minutes
Summary: Review all integer operations with examples.

Evaluation Method (Expanded)
Exit slip/quiz: Solve (+6) + (-9), (-12) ÷ (-3), (+5) × (-4). Teacher gives feedback.

Assignment (Expanded):
Solve: (-7) + (+3), (+8) - (-2), (-6) × (+3), (-15) ÷ (-5)

Follow-up Activity:
Observe real-life examples: temperature change, bank balances, elevations.

Differentiation / Inclusive Strategies
Use number lines and counters for slower learners. Allow peer-assisted problem solving.

Teacher’s Reflection (After Class)
What worked well? ___________________________________________
What needs improvement? ____________________________________
Students’ engagement level: ☑ High ☐ Medium ☐ Low