Understanding Lowest Common Multiple (L.C.M.) Mathematics Primary 4 First Term Lesson Notes Week 10

Mathematics Primary 4 First Term Lesson Notes Week 10 Lesson Plan

Learn to find the Lowest Common Multiple (L.C.M.), solve real-life problems, and apply L.C.M. in practical contexts.

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Lesson Plan:

Subject: Mathematics
Class: Primary 4
Term: First Term
Week: 10
Age: 9 years
Topic: Lowest Common Multiple (L.C.M.)
Sub-topic: L.C.M. of Numbers
Duration: 1 hour

Behavioural Objectives:

• Pupils will be able to identify multiples of numbers up to 9.
• Pupils will find the L.C.M. using different methods.
• Pupils will apply L.C.M. to solve real-life problems and quantitative aptitude.

Keywords: Lowest Common Multiple, Multiples, Quantitative Reasoning, L.C.M.

Set Induction:

• Begin by asking pupils if they have ever had to wait for two or more events to happen together, like buses or traffic lights changing. Explain that the L.C.M. helps us find when such events will occur together.

Entry Behaviour:

• Review the concept of multiples by discussing how to list multiples of simple numbers.

Learning Resources and Materials:

• Multiplication tables
• Number charts
• Whiteboard and markers
• Worksheets with L.C.M. problems
• Counters or manipulatives for hands-on practice

Building Background/Connection to Prior Knowledge:

• Connect to prior knowledge of multiplication and the concept of multiples. Reinforce that multiples are the products of a number and the whole numbers.

Embedded Core Skills:

• Problem-solving
• Critical thinking
• Mathematical reasoning

Learning Materials:

• Multiplication tables
• Number charts
• Worksheets
• Counters

Reference Books:

• Lagos State Scheme of Work
• Primary Mathematics Textbook

Instructional Materials:

• Whiteboard and markers
• Flashcards with numbers

Content:

1. Introduction to L.C.M.:
   • Define L.C.M. as the smallest number that is a multiple of two or more numbers.
2. Finding L.C.M.:
   • Listing Multiples Method: List multiples of each number and find the smallest common one.
   • Prime Factorization Method: Break each number into its prime factors, then multiply the highest powers of all primes.
   • Grid Method: Use a grid to systematically find common multiples.
3. Real-Life Applications:
   • Track races: Finding the time when multiple runners finish at the same time.
   • Traffic lights: Determining when different traffic lights will change together.

Evaluation:

1. The L.C.M. of 4 and 5 is _____. (a) 20 (b) 15 (c) 12 (d) 10
2. Find the L.C.M. of 6 and 8. (a) 48 (b) 24 (c) 36 (d) 16
3. What is the L.C.M. of 3, 4, and 6? (a) 24 (b) 12 (c) 18 (d) 15
4. The L.C.M. of 5 and 7 is _____. (a) 35 (b) 30 (c) 25 (d) 20
5. What is the smallest number that is a multiple of both 8 and 12? (a) 48 (b) 24 (c) 16 (d) 32
6. Find the L.C.M. of 2 and 10. (a) 20 (b) 10 (c) 5 (d) 15
7. The L.C.M. of 9 and 15 is _____. (a) 45 (b) 30 (c) 60 (d) 36
8. Determine the L.C.M. of 7 and 14. (a) 14 (b) 21 (c) 28 (d) 35
9. What is the L.C.M. of 4 and 9? (a) 36 (b) 18 (c) 12 (d) 9
10. The smallest number that is a multiple of 3 and 6 is _____. (a) 18 (b) 12 (c) 15 (d) 9
11. Find the L.C.M. of 8 and 10. (a) 40 (b) 20 (c) 30 (d) 16
12. The L.C.M. of 12 and 15 is _____. (a) 60 (b) 45 (c) 30 (d) 25
13. What is the smallest number divisible by both 5 and 7? (a) 35 (b) 25 (c) 30 (d) 40
14. Find the L.C.M. of 3 and 8. (a) 24 (b) 12 (c) 16 (d) 20
15. The L.C.M. of 2, 5, and 10 is _____. (a) 10 (b) 20 (c) 15 (d) 25

Class Activity Discussion:

1. How do you find the L.C.M. of 6 and 9? (Answer: List multiples or use prime factorization.)
2. Why is it important to know the L.C.M. in daily life? (Answer: For scheduling and solving problems involving repetitive events.)
3. How can you use L.C.M. to solve problems with traffic lights? (Answer: Determine when lights will change simultaneously.)
4. Explain how L.C.M. is used in track races. (Answer: Find the least time when all runners finish together.)
5. How would you find the L.C.M. of 4, 5, and 6? (Answer: List multiples or use prime factorization.)

Presentation:

1. Step 1: Review previous topic on multiplication and the concept of multiples.
2. Step 2: Introduce L.C.M. and explain different methods to find it.
3. Step 3: Facilitate discussions and practical activities to apply L.C.M. to real-life scenarios.

Teacher’s Activities:

• Explain L.C.M.: Use visual aids and examples to demonstrate how to find the L.C.M.
• Facilitate Practice: Guide pupils through exercises and real-life problem-solving.
• Monitor Progress: Check pupils’ understanding and provide feedback.

Topic: Lowest Common Multiple (L.C.M.)

1. What is the Lowest Common Multiple (L.C.M.)?

Definition:

• The Lowest Common Multiple (L.C.M.) is the smallest number that is a multiple of two or more numbers.

Example:

• For 4 and 6, the multiples of 4 are 4, 8, 12, 16, 20, etc.
• The multiples of 6 are 6, 12, 18, 24, etc.
• The smallest number that is in both lists is 12. So, the L.C.M. of 4 and 6 is 12.

2. Finding the L.C.M.

Method 1: Listing Multiples

Steps:

1. Write the multiples of each number:
   • For 3: 3, 6, 9, 12, 15, 18, 21, 24, etc.
   • For 4: 4, 8, 12, 16, 20, 24, etc.
2. Find the smallest common multiple:
   • The common multiples are 12, 24, etc. The smallest is 12.

Example:

• Numbers: 3 and 5
  • Multiples of 3: 3, 6, 9, 12, 15, 18, 21, 24, etc.
  • Multiples of 5: 5, 10, 15, 20, 25, etc.
  • Smallest common multiple: 15
  • L.C.M. of 3 and 5 is 15

Method 2: Prime Factorization

Steps:

1. Find the prime factors of each number:
   • For 6: 2 × 3
   • For 8: 2 × 2 × 2
2. Use the highest power of each prime factor:
   • Highest power of 2 is 2 × 2 × 2 = 8
   • Highest power of 3 is 3
   • Multiply these together: 8 × 3 = 24

Example:

• Numbers: 12 and 18
  • Prime factors of 12: 2 × 2 × 3
  • Prime factors of 18: 2 × 3 × 3
  • L.C.M.: 2 × 2 × 3 × 3 = 36

3. Solving Real-Life Problems Using L.C.M.

Example 1:

• Problem: A track race is held every 5 days and a swim meet is held every 8 days. How often do both events happen on the same day?
  • Solution: Find the L.C.M. of 5 and 8.
    • Multiples of 5: 5, 10, 15, 20, 25, 30, 35, 40, etc.
    • Multiples of 8: 8, 16, 24, 32, 40, etc.
    • L.C.M.: 40 days

Example 2:

• Problem: Traffic lights change every 12 minutes and 15 minutes. How often will the lights change at the same time?
  • Solution: Find the L.C.M. of 12 and 15.
    • Multiples of 12: 12, 24, 36, 48, 60, etc.
    • Multiples of 15: 15, 30, 45, 60, etc.
    • L.C.M.: 60 minutes

Practice Problems:

1. Find the L.C.M. of 4 and 9.
   • a) 18
   • b) 36
   • c) 72
2. The L.C.M. of 6 and 8 is:
   • a) 24
   • b) 30
   • c) 48
3. A bell rings every 10 minutes and a horn sounds every 15 minutes. How often will both ring at the same time?
   • a) 30 minutes
   • b) 45 minutes
   • c) 60 minutes
4. Calculate the L.C.M. of 7 and 14.
   • a) 14
   • b) 21
   • c) 28

Learners’ Activities:

• Practice Exercises: Solve problems involving L.C.M. individually and in groups.
• Real-Life Application: Discuss and solve practical problems using L.C.M.

Assessment:

• Evaluate Work: Review pupils’ answers and understanding of L.C.M. through exercises and discussions.
• Apply Knowledge: Assess ability to solve real-life problems using L.C.M.

Conclusion:

• Review Concepts: Summarize key points about L.C.M. and its applications.
• Provide Feedback: Mark pupils’ work, offer guidance, and ensure understanding of the lesson.

More Useful Links :

• All Subjects Primary 4 First Term Lesson Notes
• Highest Common Factor (H.C.F.) Mathematics Primary 4 First Term Lesson Notes Week 11