Time Goes On — Class 3 Mathematics (CBSE)
From the current NCERT Maths Mela Grade 3 book, Chapter 13. Clocks and calendars help us tell time and plan our day.
1. Why this chapter matters
Time runs our day — when we wake, study, eat, and sleep. Learning to read a clock and a calendar, and to know how seconds, minutes, hours, days, and months fit together, helps children become organised and independent.
2. Core ideas
Idea 1 — The units of time
60 seconds = 1 minute, 60 minutes = 1 hour, 24 hours = 1 day, 7 days = 1 week, 12 months = 1 year.
Method 2 — Read the clock
The short hand shows the hour; the long hand shows the minutes. Long hand on 12 = o'clock; on 6 = half past.
Skill 3 — Read the calendar
A calendar shows the days of the week and the months of the year, and helps us find dates.
3. Worked examples
Example 1: The short hand is on 3 and the long hand on 12. What time is it?
It is 3 o'clock.
Example 2: The short hand is between 4 and 5, the long hand on 6. What time?
It is half past 4 (4:30).
Example 3: How many days are there in a week, and how many months in a year?
7 days in a week and 12 months in a year.
4. Activity corner
Make a paper clock with two hands. Set it to show 2 o'clock, half past 7, and your school start time. Then circle today's date on a calendar. Write:
- The times I showed
- Today's day and date
- The maths idea (reading clocks and calendars)
5. Common mistakes
- Mistake: Mixing up the hour hand and the minute hand. Fix: The short hand = hour, the long hand = minutes.
- Mistake: Saying "half past" without moving the hour hand. Fix: At half past, the hour hand sits between two numbers.
- Mistake: Forgetting the number of days or months. Fix: Remember 7 days in a week and 12 months in a year.
6. How to write better answers
- Look at the short hand for the hour.
- Look at the long hand for o'clock or half past.
- For the calendar, find the day, date, and month.
- Use the correct unit (minutes, hours, days).
7. Practice set
- How many minutes are there in one hour?
- The short hand is on 8 and the long hand on 12. What time is it?
- How many days are there in one week?
- How many months are there in one year?
- What time is half past 6?
- How many hours are there in one day?
8. Answer key
- 60 minutes in one hour.
- 8 o'clock.
- 7 days in one week.
- 12 months in one year.
- Half past 6 is 6:30.
- 24 hours in one day.
9. Quick revision
- 60 seconds = 1 minute; 60 minutes = 1 hour; 24 hours = 1 day.
- 7 days = 1 week; 12 months = 1 year.
- Short hand = hour; long hand = minutes.
- Long hand on 12 = o'clock; on 6 = half past.
- A calendar shows days, dates, and months.
