Time Goes On Chapter Notes | Mathematics for Class 3 (Maths Mela) PDF Download

Introduction

Let's Understand With a Story

Once upon a time, there was a little girl named Mia. Mia loved playing outside with her friends and going on adventures. One day, her mom said they were going to have a special picnic in the park on Wednesday.

"But how will we remember when Wednesday is?" Mia asked, looking puzzled. Mom smiled and pointed to a colorful calendar hanging on the wall. "We'll use this!" she said.

 She showed Mia the Days of the Week and the Names of the Months. Then Mom circled "Wednesday, 22nd May" on the calendar."Now we know when our picnic is!" Mom said cheerfully. And so, Mia learned that the calendar was like a magical guide that helped her family plan fun adventures together.

Understanding Calendars

Imagine you have a special book that helps you know what day it is, plan events, and remember important dates like birthdays and holidays. This special book is called a calendar!

Days and Months

• A year has 365 days, but a leap year has 366 days (every fourth year).
• In a leap year, February has 29 days instead of 28.
• There are 12 months in a year:
• 31 days: January, March, May, July, August, October, December.
• 30 days: April, June, September, November.
• February: 28 days (29 days in a leap year).
• A year has 52 weeks.
• Each week has 7 days:

  Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday.

Writing Dates

• When we write a date, we first write the number of the day, then the name of the month, and finally the year. 
• We can use dots or slashes to separate them.
  For example, if it's May 6, 2024, we can write it as 6.05.2024 or 6/05/2024.

Examples

• If someone tells you to meet them on 25th June, you'll know it's the 25th day of June.
• On your birthday, your family might write the date like this: 10.12.2013 (10th December 2013) to remember your special day!

Isn't it cool how the calendar helps us keep track of time and remember special moments?

Age Fun

Family Ages

Let's talk about Mia's family.

• Mia is 8 years old, and her mom is 32 years old. 
• When Mia's mom was born, her grandma was already 50 years old. Can you guess her grandma's age?
• Yes, you guessed it right! Mia's grandma is 58 years old now!
• When Mia was born her Grandma was 50 years old , now her age will be 50 + 8 = 58 years old.

Siblings' Ages

Consider Lily and her brother. 

• Lily is 10 years old. If she is twice as old as her brother, can you guess the age of his brother?
• Since Lily is twice as old as her brother, her brother is half her age. That means her brother is 5 years old.

Lily's Birth Certificate

Birth Certificate is a special document which contains important information about Lily's birth, like her birth date and her parents' names, making it a special keepsake for her family.

• Lily was born on 9th May 2014. 
• To find out her age on her birthday in 2024, we count the years from when she was born to 2025. That's 10 years!
• To find out her age in 2030, we count the years from when she was born to 2030. That's 16 years!
• Lily's birth certificate was issued 9 days after she was born, on 18th May 2014.

These simple examples help us understand how ages are connected within families and how we can figure out different ages and dates using basic math.

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.Thirty-five minutes past 4 or 4:35
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.Twenty-five minutes to 5

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:

Let's Practice

(i) Total number of Sundays in November month  ______________________________.
(ii) Write the dates in this month that fall on Thursday ___________________________.
(iii) Three days after 22nd November  is  _________________November . The day on this date is _____________________.
(iv) A school closes on November 7 for 15 days. The date on which the school will open is _____________________.

Sol:

(i) No. of Sundays = 5
(ii) The dates that fall on Thursday in this month are 5, 12, 19, 26.
(iii) Three days after 22nd November is 25th November , and the day on this date is Wednesday.
(iv) A school closes on November 7th for 15 days. The date on which the school will open is 22th November .

2. Write the time that is shown in each clock :

Sol: 

In summary, understanding the structure of a year, months, and weeks , knowing about time , age helps us organize time efficiently and recognize important patterns like leap years, which occur every four years.