Time Class 3 Notes Maths

Time

Time is a way to measure and quantify the duration or sequence of events. It's a concept that helps us understand when things happen, how long they last, and in what order they occur.

What is a Clock?

A clock is used to measure time. A clock has two hands— the short hand called the hour hand and the long hand called the minute hand.

• An hour (h) and minute (min) are the standard units for the measurement of time.
• The hour hand shows the hour and the minute hand shows the minutes before and after the hour.
• The minute hand goes around the clock once in 1 hour. The hour hand goes around the clock once in 12 hours.
  
• When the minute hand moves all the way round the clock, i.e., from 12 to 12, an hour passes.

60 minutes = 1 hour  
1 day = 24 hours

Telling Time to the Half Hour

In the clock shown alongside, the hour hand is between 9 and 10 and the minute hand points to 6. The coloured part shows that the long hand or minute hand has moved half way round.
When the minute hand moves half way round the face of the clock, half an hour has passed and we say that it is half past nine.
∴ Half past nine can also be written as 9:30.

60 minutes = 1 hour
30 minutes = One-half of an hour

Observe the following clocks

Telling Time to the Nearest Five Minutes

• When the hour hand (short hand) moves from one digit to the other, 1 hour passes.
• When the minute hand (long hand) moves from one digit to the other, 5 minutes pass.
  
• Count the minutes all around the clock by 5s, starting at 12.
  The numbers outside the clock show the count.
• So, we skip count by 5s to find the time to the nearest five minutes. There are many ways of reading and telling the time.
  

When the minute hand has moved past 6, we say the time in the following two ways:

1. First Way : The hour hand is between 4 and 5, so  the time is after 4 o’ clock. The minute hand is at 7. Starting at 12 and counting ahead by 5s to 7, we get 35 minutes. 

So, we say that the clock shows the time 35 minutes after 4 or 35 minutes past 4.

2. Second Way: The hour hand is between 4 and 5, so the time is before 5 o’ clock. The minute hand is at 7. Starting at 12 and counting back by 5s to 7, we get 25 minutes. We write 25 minutes to 5 to tell the time because there are 25 minutes left to 5 o’ clock.

Examples:

Telling Time to the Quarter Hour

Let us read time on the clocks given below:
The minute hand has moved one quarter (one-fourth) of the circle in moving from 12 to 3.
So, 1 / 4 of an hour = 15 minutes.

• The time shown on the clock is 12:15 or Fifteen minutes past twelve, which we generally read as quarter past twelve.
  
• Both the clocks A and B given show the same time which can be read in clock A as: 8:45 or Forty-five minutes past 8.
• In clock B, the same time can be read as: Fifteen minutes to nine or Quarter to nine.

Examples: 

Calendar

A calendar is a system used to organize and record time, typically based on the cycles of the Earth's movements, such as the rotation of the Earth on its axis and its orbit around the Sun. 

• Calendars help us keep track of days, weeks, months, and years, allowing us to plan and schedule events, religious observances, agricultural activities, and more. 
• Calendar is a table showing the days, weeks and months of a year. 
• It displays all the dates and days of the week. There are 7 days in a week.

Days of Week in Order:

• Monday is the first day of the week and Sunday is the last day of the week.
• There are 12 months in a year.
• There are 365 days in an ordinary year and the month of February has 28 days. But every fourth year, February has 29 days and the year has 366 days. It is called a leap year.
• The calendar given below shows the months of the year in order:

Calendar 2024

• Months are also identified by their position in the year
• All the months do not have equal number of days. Some have 30, some have 31 and one month has even less.

  
  

Month having 28 or 29 days February

Writing a Date

• A calendar date helps us to identify a specific day represented within the calendar.
  For example: The first Monday of January 2019 as given in the calendar for 2019 is identified as 
• 7th January 2019 which can be written in short form as 7/01/2019 or 07-01-2019 or 07.01.2019, where 01 represents the month number, 2019 the year and 07 the day of the month.
• The format can be written generally as: dd/mm/yyyy, where dd– day, mm– month, yyyy– year 
• Let us see what the date on the third Sunday of August 2019 is? 
  The day on the third Sunday is 18. The month number is 08 and the year is 2019.
  ∴ Required date is 18/08/2019 or 18.08.2019.