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 Activity (10 Minutes):  

 Pass pass  

 In "Pass Pass," children form a circle. Choose any number, for example 5. Then each child starts counting from one. When they reach 5 or multiples of five, they have to say pass. If they don't say pass, that child is out.  The game continues until only one child remains.(NB: Change the number after each round) 

 Main Activity (65 minutes): 

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

 Game Time  ( 25 minutes ) 

 

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

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

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

 The first common number they step on is the LCM ( NB: Repeat the activity with different number ) 

 

 Time to solve ( 20 Minutes) 

 Give simple examples: ( Divide 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? 

 

 

 Review Questions (5 minutes): 

 Ask: What strategies helped you solve the problems quickly? 

 Encourage peer teaching—students explain their solutions to classmates. 

 Follow Up Task (10 minutes): 

 Home work  

 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