📝

NCERT Mathematics Class 3 - Chapter 7: Time Goes On - Notes

CBSEClass 3Mathematicsसमय बीतता है

Learning Objectives

  • Read time on a clock (hours and minutes)
  • Understand the concepts of a.m. and p.m.
  • Learn about the calendar: days, weeks, months, and year
  • Calculate time duration and solve problems on time

Key Concepts

Reading a Clock

A clock has two hands. The short hand shows the hour and the long hand shows the minutes. When the long hand is on 12, it is exactly that hour (like 3 o'clock). When the long hand is on 6, it is half past that hour (like half past 3 or 3:30). Each small mark on the clock face is 1 minute, and there are 60 minutes in one hour.

A.M. and P.M.

A.M. means the time from midnight (12:00 at night) to noon (12:00 in the afternoon). P.M. means the time from noon to midnight. So 8:00 a.m. is morning time when you go to school, and 8:00 p.m. is evening time when you might be at home after dinner.

Calendar

A week has 7 days: Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday. A year has 12 months. Some months have 30 days, some have 31 days, and February has 28 or 29 days. A year has 365 days (366 in a leap year).

Finding Duration

To find how long something takes, subtract the start time from the end time. If a movie starts at 3:00 p.m. and ends at 5:00 p.m., it is 2 hours long. If your lunch break is from 12:30 to 1:00, it is 30 minutes long.

Important Terms

  • Hour Hand: The short hand on a clock that shows the hour
  • Minute Hand: The long hand on a clock that shows the minutes
  • A.M.: Time from midnight to noon (morning hours)
  • P.M.: Time from noon to midnight (afternoon and evening hours)
  • Duration: How long something takes from start to finish
  • Leap Year: A year with 366 days; February has 29 days

Quick Revision

  • 1 hour = 60 minutes
  • 1 day = 24 hours
  • 1 week = 7 days
  • 1 year = 12 months = 365 days (or 366 in a leap year)
  • The short hand shows hours, the long hand shows minutes
  • A.M. is morning time, P.M. is afternoon and evening time
  • Months with 31 days: January, March, May, July, August, October, December
NCERT Mathematics Class 3 - Chapter 7: Time Goes On - Notes | EduMunch