Time for Class 4

In this chapter, we will learn how to read and understand time using a clock. We will gain the necessary skills to accurately read and interpret the different components of a clock such as the hour and minute hands. This knowledge will enable us to effectively manage our time and be punctual in our daily activities.

What is Time?

Time is defined as the duration in which all things happen. Time is an exciting concept that guides our daily routines from waking up in the morning to going to bed at night. It helps us organize our day and understand when different events occur.

Measurement of Time

Time is measured by a clock. A clock typically has a round face with 12 numbers on it to show the time. Inside the clock, there are three hands:

→ The short hand indicates the hours.
→ The long hand indicates the minutes. 
→ The thin hand indicates the seconds.

Two Formats of Time

Time format is a method of representing time in hours, minutes, and seconds. The two most common types of time formats are 12-hour and 24-hour clocks.

12-Hour Format:

In the 12-hour format, we divide the day into two parts:

Ante Meridiem (AM) and Post Meridiem (PM).

→ AM is from midnight (12:00 AM) to midday (12:00 PM).
→ PM is from midday (12:00 PM) to midnight (12:00 AM).

The cycle of the day is shown as:

This format is commonly used to display time on regular clocks and watches. To determine the time in the 12-hour system, we use digits 1-12 followed by "AM" or "PM" to indicate whether it is morning, afternoon, evening, or night.

24-Hour Format:

The 24-hour format is also known as the international time format. In this format, the entire day is divided into 24 hours and we don't use "AM" or "PM".

→ The hours run from 00:00 (midnight) to 23:59 (just before the next midnight).
→ It is a continuous count of time so there is no need to switch between AM and PM.

The cycle of the day is shown as:

Let's look at an example to clearly understand this concept.

For example, 8:15 AM in the 12-hour format is equivalent to 08:15 in the 24-hour format and 9:45 PM in the 12-hour format is equivalent to 21:45 in the 24-hour format.

This clock shows both 12-hour and 24-hour formats.

Units of Time

Some common units of time are years, months, weeks, days, hours, minutes, seconds, etc.

Conversion of one unit to another unit

→ 1 year = 12 months

Note:

1. 1 month can have 28, 29, 30 or 31 days depending upon the month. 
2. 1 year = 365 days
3. 1 leap year = 366 days
4. There are 28 days in February in a year whereas there are 29 days in February in a leap year.
5. 1 year has 52 weeks and one day whereas a leap year has 52 weeks and two days.

→ 1 week = 7 days
→ 1 day = 24 hours
→ 1 hour = 60 minutes
→ 1 minute = 60 seconds
→ 1 hour = 3600 seconds
→ 1 second = 100 centiseconds
→ 1 second = 1000 milliseconds

Terms related to days

"Let's understand some important words related to time:

→ 'Today' means the day we are experiencing right now.

→ 'Yesterday' is the day that occurred before today. In other words, it is the day that came before today. So, when we talk about yesterday, we are referring to the previous day.

→ 'Tomorrow' is the day that will follow today. It is the day that comes after today. So, when we talk about tomorrow, we are referring to the next day."

Let’s understand by taking an example:

If today is Monday, then yesterday was Sunday and tomorrow will be Tuesday.

Quarters of Time

A quarter of time refers to a fraction of time. So, when we say a quarter of the time, we are talking about dividing time into four equal segments. Each segment represents one quarter, which is represented by the following figure:

Example 1: Which of the following options shows the time which is equal to 65 minutes more than 8:05?

a)
b)
c)
d)

Answer: b)

Explanation: Time which is equal to 65 minutes more than 8:05 = 8:05 + 65 minutes
= 8:05 + 1 hour + 5 minutes 
= 9:05 + 5 minutes
= 9:10

Example 2: How many minutes are present in 1 day 5 hours? 

a) 1700 minutes
b) 1720 minutes
c) 1740 minutes
d) 1760 minutes

Answer: c) 1740 minutes

Explanation: Minutes in 1 day 5 hours = 1 day + 5 hours 
                                                         = 24 hours + 5 hours
                                                         = 29 hours
                                                         = (29 × 60) minutes
                                                         = 1740 minutes