Decimals

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Subject: Mathematics

Semester: 1

Period: 3

Week: 15

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School Name:
Teacher’s Name:
Subject: Mathematics
Grade Level: Grade 6
Date: Week 15
Lesson Duration: 45 minutes
Week & Period: Week 15, Period 3
Topic: Decimals
Sub-topic: Multiplication of Decimals

Learning Objectives
By the end of the lesson, students should be able to:

• Multiply a decimal by a whole number.
• Multiply decimals by decimals.
• Correctly place the decimal point in the product.
• Apply multiplication of decimals to real-life problems.

Previous Knowledge
Students already know multiplication of whole numbers and addition/subtraction of decimals.

Instructional Materials
Mathematics textbook for Grade 6, abacus, charts with decimal multiplication examples.

Lesson Development – ABC Model
A – Anticipation (Warm-up / Starter)
Time: 5–10 minutes
Teacher asks: If 1 kg of rice costs L$2.5, how much will 4 kg cost?

B – Building Knowledge (Main Lesson Body)

Time: 25–30 minutes

1. Steps for Multiplying Decimals
2. Ignore the decimals at first and multiply the numbers as if they are whole numbers.
3. Count the total number of decimal places in both factors.
   • Example: 2.5 (1 decimal place), 0.24 (2 decimal places) → total = 3 decimal places.
4. Place the decimal point in the product so that it has the same number of decimal places as the total counted.

 

2. Worked Examples

Example 1 – Decimal × Whole Number:
0.3×4
= Multiply as whole numbers → 3×4=12
= Place decimal (1 decimal place total) → 1.2

Example 2 – Decimal × Decimal:
2.5×0.2
= Multiply as whole numbers → 25×2=50
= Count decimals → (1 + 1 = 2)
= Product = 0.50 (or simply 0.5)

Example 3 – Decimal × Decimal:
1.25×0.6
= Multiply as whole numbers → 125×6=750
= Count decimals → (2 + 1 = 3)
= Product = 0.750 = 0.75

Example 4 – Larger Decimal Multiplication:
3.24×1.5
= Multiply as whole numbers → 324×15=4860
= Count decimals → (2 + 1 = 3)
= Product = 4.860 = 4.86

Example 5 – Money Problem:
A mango costs L$2.35. If Peter buys 4 mangoes, how much does he pay?
2.35×4=9.40.
Peter pays L$9.40.

Example 6 – Measurement Problem:
The length of one tile is 0.45 m. What is the total length of 12 tiles placed end to end?
0.45×12=5.40.
The total length = 5.4 meters.

Example 7 – Area Problem:
A rectangle has length = 2.5 m and width = 1.2 m. Find the area.
Area = 2.5×1.2=3.00.
The area is 3.0 m².

 

3. Learners’ Activities (Expanded)

• Students solve guided examples on decimal multiplication in pairs.
• Learners create shopping word problems (e.g., buying bread, milk, fruits in decimals of currency) and exchange with classmates to solve.
• Groups measure classroom objects (length in meters/centimeters) and multiply to calculate approximate areas.
• Peer teaching: one learner explains decimal placement while others verify answers.

 

4. Assessment Checks (Quick Tests)
5. Solve:
   • 7×3
   • 15×0.4
6. A pencil costs L$0.75. How much will 8 pencils cost?
7. Find the product of 4.2×1.5.
8. A rope measures 2.35 m. What is the length of 5 such ropes?
9. Calculate the area of a rectangle: length = 1.25 m, width = 0.8 m.

 

5. Notes (Expanded & Detailed)

• Multiplying decimals follows the same process as multiplying whole numbers.
• The only difference is the placement of the decimal point.
• Count the decimal places in both factors and ensure the product has the same number of decimal places.
• Decimal multiplication is applied in daily life: money (prices, costs), measurements (length, mass, time), and geometry (areas, volumes).

 

6. Assignment
7. Multiply:
   • 25×3
   • 06×0.2
   • 5×0.04
   • 08×2.5
8. Solve these word problems:
   A bottle of juice costs L$1.75. How much do 6 bottles cost?
   ii. A table has length = 1.25 m and width = 0.85 m. Find the area.
   iii. Musa buys 3.5 kg of rice at L$2.45 per kg. How much does he pay?

C – Consolidation (Conclusion & Assessment)
Time: 5–10 minutes
Summary: Multiplying decimals requires multiplying as whole numbers and adjusting the decimal place.

Evaluation Method (Expanded)
Exit slip/quiz: Solve 0.9 × 6 and 3.25 × 0.2.
Teacher will collect slips and provide oral feedback.

Assignment (Expanded):
Solve 1.35 × 2.5 and 4.8 × 0.75.

Follow-up Activity:
Students practice creating and solving market-based word problems.

Differentiation / Inclusive Strategies
Provide place value charts for struggling learners; challenge faster learners with 3-decimal place multiplication.

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