Exploring Time and Duration in Mathematics

Learning together with Mutiara

Introduction to Time and Duration

Assalamualaikum siblings! Welcome to another session of learning together with Mutiara.
Today, we will be exploring the concept of time and duration in mathematics, specifically in the context of a second-grade lesson.
We will be following the Merdeka Curriculum, focusing on the chapter titled 'Waktu dan Durasi'
In this lesson, we will examine the concept of time as indicated by clocks and the duration it takes for various activities.

Let's start by examining the clock notation in diagram A:
- The long green hour hand points to the number 12, indicating 9:00
- The short red minute hand points to the number 9
Next, in diagram C, we see the clock indicating the time when the students arrive at the train station.
- The long green hour hand has moved 10 scales or 10 minutes ahead from diagram A
- Combining the time in diagram A (9:00) and the 10-minute shift, the students arrived at 9:10.
Moving on to diagram D, the clock shows the time when the train arrives at its destination.
- The long green hour hand begins at 5 and moves 18 scales or 18 minutes ahead.
- By adding 18 minutes to the time in diagram C (9:25), we get the arrival time as 9:43.
Lastly, diagram E indicates the start of the adventure.
- The short red minute hand is at 10, and the long green hour hand is at 12, representing 10:00.

Let's calculate the duration for various activities:
1. When the long hand moves from 9:10 to 9:25, it covers 15 scales. Each scale represents 1 minute, so the duration is 15 minutes.
2. How many scales does the long hand cover from 9:10 to 9:25? By subtracting 25 - 10 = 15, the duration is 15 scales.
3. From 9:25 to 9:43, the long hand moves 18 scales or 18 minutes. Adding this to the previous time, we get 9:43.
4. Finally, the students begin their adventure at 10:00. The short hand is at 10, and the long hand is at 12.
Challenge the students to take a clock from their home and rotate it to match the diagrams A, B, C, D, and E, and determine the respective times.

Let's explore the rotation of clock hands:
- The long hand takes 60 minutes to complete a full rotation.
At the same time, the short hand moves 1 hour, representing the transition from one number to the next.
- The second hand takes 60 seconds to complete a full rotation.
Simultaneously, the long hand moves 1 minute.
Therefore, 60 minutes equals 1 hour, and 60 seconds equals 1 minute.
Now, observe the clock diagrams:
- The first diagram shows 12:00, indicating midnight or the beginning of the day.
The next few hours are labeled as dini hari, pagi, siang, sore, petang, and malam.
- The second diagram represents the rotation of the clock throughout a day, starting from midday (12:00) until the next midday.
- Note that the cycle between 12:00 PM and 12:00 AM comprises 24 hours, representing a full day.
Count the total hours on the clock diagram and confirm that there are 24 hours in a day.

Let's solve some problems related to time and duration:
1. Duration of playtime: The duration of my playtime is 1 hour.
2. Time of the day start: The day starts at 6:00 AM.
3. Time 50 minutes before 13:40 PM: The time is 12:50 PM.
4. Time 40 minutes after 22:40 PM: The time is 23:20 PM.
Encourage students to answer the questions by applying their knowledge of time and duration.