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Subject: Mathematics
Semester: 1
Period: 3
Week: 14
School Name:
Teacher’s Name:
Subject: Mathematics
Grade Level: Grade 6
Date: Week 14
Lesson Duration: 45 minutes
Week & Period: Week 14, Period 3
Topic: Decimals
Sub-topic: Addition and Subtraction of Decimals
Learning Objectives
By the end of the lesson, students should be able to:
- Align decimal points correctly when adding and subtracting decimals.
- Add and subtract decimals with equal and unequal decimal places.
- Add and subtract decimals from whole numbers.
- Solve real-life word problems involving decimals.
Previous Knowledge
Students already know addition and subtraction of whole numbers and basic decimal notation.
Instructional Materials
Mathematics textbook for Grade 6, place value charts, money ( L$), measuring tapes.
Lesson Development – ABC Model
A – Anticipation (Warm-up / Starter)
Time: 5–10 minutes
Teacher asks: If you buy an orange for L$2.50 and a mango for L$3.25, how much do you spend?
B – Building Knowledge (Main Lesson Body)
Time: 25–30 minutes
- Rule for Adding and Subtracting Decimals
- When adding or subtracting decimals, the most important step is to align the decimal points.
- This ensures that digits with the same place value (ones, tenths, hundredths, thousandths) are lined up correctly.
- Tip: If one number has fewer decimal places, fill in with zeros.
Examples of Alignment:
2.35
+ 1.40
3.75
6.003
- 2.450
3.553
- Worked Examples
Example 1 – Simple Addition:
2.35+1.42.35 + 1.42.35+1.4
= 2.35+1.402.35 + 1.402.35+1.40 (add a zero)
= 3.75
Example 2 – Simple Subtraction:
5.07−2.55.07 - 2.55.07−2.5
= 5.07−2.505.07 - 2.505.07−2.50 (add a zero)
= 2.57
Example 3 – Subtraction with Borrowing:
6.003−2.456.003 - 2.456.003−2.45
= 6.003−2.4506.003 - 2.4506.003−2.450 (add zero)
Borrow across place values carefully:
= 3.553
Example 4 – Adding Whole Numbers and Decimals:
7+3.257 + 3.257+3.25
= 7.00+3.257.00 + 3.257.00+3.25
= 10.25
Example 5 – Word Problem (Buying Goods):
Mary bought oranges for L$2.35 and bananas for L$1.75. How much did she spend altogether?
Solution:
2.35+1.75=4.102.35 + 1.75 = 4.102.35+1.75=4.10.
She spent L$4.10 in total.
Example 6 – Word Problem (Subtracting Money):
James has L$10. He buys bread for L$3.75. How much money is left?
Solution:
10.00−3.75=6.2510.00 - 3.75 = 6.2510.00−3.75=6.25.
He has L$6.25 left.
- Learners’ Activities (Expanded)
- Students solve addition and subtraction problems in pairs (teacher provides fractions and decimals mixed with whole numbers).
- In groups, learners create their own word problems involving buying and selling goods, measuring lengths, or adding distances.
- Students practice writing decimals in money form (L$0.50, L$2.75, L$12.05).
- Learners use rulers to measure lengths with decimals (e.g., 3.2 cm + 2.45 cm).
- Assessment Checks (Oral & Written)
- Solve:
- 2+2.45
- 01−2.9
- Add L$4.75 and L$3.55.
- Subtract L$9.50 from L$15.00.
- John walks 2.35 km in the morning and 3.65 km in the evening. How far did he walk in total?
- A container has 5.07 liters of water. 2.58 liters is poured out. How much water remains?
- Notes (Expanded & Detailed)
- Always align decimal points in addition and subtraction.
- Add zeros to equalize decimal places before calculating.
- When subtracting, borrow carefully across decimal places just as in whole numbers.
- Decimals appear in real-life situations: money, measurements, distances, weights, and time.
- Assignment
- Add:
- 35+4.6
- 005+3.25
- L$15.75 + L$23.80
- Subtract:
- 5−13.75
- 007−2.89
- L$100.00 – L$72.45
- Word problems:
Mary bought sugar for L$8.50 and milk for L$12.75. How much did she spend in total?
ii. Musa measured a rope as 4.5 m. He cut off 2.35 m. How long is left?
iii. A taxi driver earned L$250.75 on Monday and L$375.50 on Tuesday. How much did he earn in both days?
C – Consolidation (Conclusion & Assessment)
Time: 5–10 minutes
Summary: Addition and subtraction of decimals require careful alignment of decimal points.
Evaluation Method (Expanded)
Exit slip/quiz: Solve 4.6 + 2.35 and 8.02 – 3.47.
Teacher will collect slips and provide oral feedback.
Assignment (Expanded):
Solve 5.21 + 3.007 and 7.35 – 2.125.
Follow-up Activity:
Students calculate total prices of items in a shop.
Differentiation / Inclusive Strategies
Support struggling learners with money examples; advanced learners solve more complex decimal problems.
Teacher’s Reflection (After Class)
What worked well? ___________________________________________
What needs improvement? ____________________________________
Students’ engagement level: ☑ High ☑ Medium ☑ Low