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Session 31: The Least Common Multiple (LCM)

Session Title

The Multiple Mysteries 

Objective

By the end of this session, students will be able to:


1. Understand the concept of the Least Common Multiple (LCM)



2. Find the LCM of the given numbers using different methods.



3. Develop problem-solving and teamwork skills 

Topics

The Least Common Multiple (LCM) is the smallest multiple that two or more numbers share.


It is useful in real-life applications, such as scheduling events, solving fraction problems, and understanding patterns.

Material Required

Board & Chalk 

Before starting the class, draw a number grid ( up to 50 ) on the floor

Methodology

Activity-based Learning: Physical activity and group work.


Experiential Learning: Relating LCM to real-life situations.

Session Duration 

 90 Minutes

Introduction ActivityActivity(10

Minutes) 

GAME TIME

Pass pass - (10 Minutes)


In "Pass Pass," children form a circle. A target number is chosen. Starting with the first child, they count aloud in sequence. When a child's count reaches a multiple of the target number, they say "Pass" instead of the number. The next child continues the count. The game continues until only one child remains.(NB: Change the number after each round)


Main Activity(70 minutes)

Main Topic/ Activity


Objective: Help students relate LCM to everyday life.


Tell a short story:- ( 20 minutes )


Two friends, Arya and Rahul, love visiting a park. Arya visits every 3 days, and Rahul visits every 4 days. If both visit the park today, when will they meet again?


Ask students to think and predict: “Will they meet again in a week? In 10 days?”


Guide them to count the days until both are at the park together (on the 12th day).


Explain

Explnumbers atthat the Least Common Multiple (LCM) of 3 and 4 is 12—the smallest number that both 3 and 4 can divide into evenly.



Game

DEMO TIMETime  ( 3025 minutes )


    1.

  1. Draw a number grid on the floor (1–50)


    2. 2.

  2. Call out two numbers (e.g., 4 and 6)


    3. 3.

  3. Students take turns hopping on the multiples (4, 8, 12… and 6, 12, 18…)


    4. 4.

  4. The first common number they step on is the LCM

     ( NB: Repeat the activity with different number )


Time

TIMEto TO SOLVE:solve ( 20 Minutes)


Give simple examples: ( DevideDivide students into small groups)


  • LCM of 2 and 5 

→ Multiples: (2, 4, 6, 8, 10, 12…) and (5, 10, 15…) → LCM is 10.


  • LCM of 6 and 8

→ Multiples: (6, 12, 18, 24…) and (8, 16, 24…) → LCM is 24.


  • A bell rings every 6 minutes, and another bell rings every 8 minutes. After how many minutes will both bells ring together?


  • A school organizes a sports day every 5 years, and a cultural fest every 7 years. How many years later will both events happen together again?


Expected Learning  Outcome:


Knowledge building-

  • Concept of LCM

  • Method to find LCM


Skill Building-

  • Logical thinking

  • Strengthens speed and accuracy

  • Team work 


Review Questions/Assessment/TasksQuestions(5


minutes)

Ask: What strategies helped you solve the problems quickly?


Encourage peer teaching—students explain their solutions to classmates.


Follow up Task

 (10minutes)


Home work:work ( 10 minutes)

1.Two farmers plant crops—one plants every 9 days, and the other every 12 days. In how many days will they plant on the same day again?


2.Two buses leave a station at the same time—one after 12 minutes, the other after 15 minutes. When will they leave together again?

Expected Learning  Outcome:

Knowledge building-

  • Concept of LCM

  • Method to find LCM

Skill Building-

  • Logical thinking

  • Strengthens speed and accuracy

  • Team work 



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