Summary
Chapter 12 of the Class 4 Mathematics NCERT textbook (Maths Mela), "Ticking Clocks and Turning Calendar", introduces students to reading time using AM/PM and 24-hour digital clock formats, understanding the relationship between hours and minutes (1 hour = 60 minutes, half hour = 30 minutes, quarter hour = 15 minutes), counting days and weeks on a calendar, and exploring leap years. Download the PDF and read a summary and Q&A below.
- Leap Years and the Calendar — The chapter opens with Parv's birthday on 29 February 2016, introducing the concept that years with 29 February are called leap years. Leap years have one extra day, making them 366 days long, and occur every four years. Students compare February 2024 (a leap year) and February 2025 (not a leap year) using actual calendar grids.
- Reading and Writing Dates — Students learn the DD/MM/YYYY date format, for example 04/07/2024 is read as 4th July 2024. Activities include finding who is older between two children born on different dates, and checking the manufacturing and expiry dates on biscuit packets to calculate shelf life in months and days.
- AM, PM, and the 24-Hour Digital Clock — The chapter explains that 8:00 AM and 8:00 PM look the same on a clock face but refer to different times of day. Students fill in a conversion table mapping familiar AM/PM times to 24-hour digital format — for example, 1:00 PM becomes 13:00 hours and 11:45 PM becomes 23:45 hours.
- Hours and Minutes in Daily Life — A clock-face activity follows a doctor's full day from 6:00 AM to 6:00 AM the next day, with students calculating hours spent on each activity and confirming that a full day has 24 hours. Story problems about Raghav buying milk (8:20 AM to 8:35 AM = 15 minutes) and Akira travelling to school (8:00 AM + 15 min = 8:15 AM) reinforce adding minutes to a given time.
Key points & formulas
- 01Leap years occur every four years and have 366 days because February has 29 days instead of 28.
- 02The DD/MM/YYYY date format is used throughout the chapter for writing and reading dates.
- 03AM stands for the hours from midnight to noon; PM stands from noon to midnight.
- 0424-hour digital clock time runs from 00:00 (midnight) to 23:59 — afternoon hours are simply 12 added to the PM hour.
- 051 hour = 60 minutes; half an hour = 30 minutes; quarter of an hour = 15 minutes; three-quarters of an hour = 45 minutes.
- 06Students practise adding minutes to a clock time using story problems involving characters like Raghav and Muneera.
- 07A day has 24 hours in total, confirmed by tracing a doctor's schedule from one 6:00 AM to the next.
- 08Students explore months in Hindu, Islamic, Sikh, and other community calendars and compare them with the English calendar.
Frequently asked questions
01What is the main topic of Chapter 12 in Class 4 Maths Mela?
Chapter 12, Ticking Clocks and Turning Calendar, covers reading time using AM/PM and 24-hour digital clocks, understanding leap years, using the DD/MM/YYYY date format, and calculating elapsed time in hours and minutes.
02What is a leap year according to this chapter?
A leap year is a year that has 29 February instead of 28, making it 366 days long. The chapter states that leap years occur every four years. 2024 is given as an example of a leap year.
03How many days does February have in a leap year versus a normal year?
In a leap year February has 29 days, as shown in the calendar for February 2024. In a normal year, such as February 2025 shown in the chapter, it has 28 days.
04What is the difference between AM and PM?
AM refers to times from 12:00 midnight up to 12:00 noon, and PM refers to times from 12:00 noon up to 12:00 midnight. The chapter shows 8:00 AM (morning) and 8:00 PM (night) as an example of why the label matters.
05How do you convert AM/PM time to 24-hour digital clock time?
For AM times, the 24-hour time is the same (e.g., 7:15 AM = 07:15 hours). For PM times, add 12 to the hour (e.g., 1:00 PM = 13:00 hours, 5:20 PM = 17:20 hours). Midnight is 00:00 and noon is 12:00.
06How many minutes are in one hour, half an hour, and a quarter hour?
1 hour equals 60 minutes, half an hour equals 30 minutes, and a quarter of an hour equals 15 minutes. The chapter also states that three-quarters of an hour equals 45 minutes.
07What story problems are used in this chapter to practise adding time?
Raghav leaves home at 8:20 AM and returns at 8:35 AM, so the elapsed time is 15 minutes. Muneera starts reading at 4:15 PM and finishes in 45 minutes. Raghav also does homework starting at 10:20 AM and takes 25 minutes to finish.
08How many hours are in a full day?
The chapter shows a doctor's schedule from 6:00 AM one day to 6:00 AM the next day, confirming that a full day has 24 hours total.
09What date format does this chapter teach?
The chapter teaches the DD/MM/YYYY format. For example, 04/07/2024 is read as 4th July 2024. Students also practise comparing birth dates to find who is older.
10What is the calendar exploration activity in this chapter?
Students are asked to explore the Hindu, Islamic, Sikh, or another community calendar with the help of parents and teachers, finding when the year begins, matching month names with the English calendar, and identifying new moon and full moon patterns.
11What activity uses a biscuit packet in this chapter?
Students check the manufacturing and expiry dates printed on a biscuit packet wrapper, then calculate how old the packet is and how many months and days are left before the biscuits expire.
12Why do two different times both show 8:00 on a clock?
A 12-hour clock face shows each hour twice — once in the morning (AM) and once in the evening or night (PM). The chapter introduces AM and PM labels, and the 24-hour digital format (08:00 for morning, 20:00 for night), to remove this ambiguity.
More chapters in Maths Mela
Read Chapter 12 of Maths Mela, the Class 4 Mathematics NCERT textbook (2026-27 edition), online for free: the complete chapter as published by NCERT with every diagram, solved example and exercise, with step-by-step solutions, answers and revision notes. Open the NCERT PDF above, or browse all NCERT Class 4 textbooks.
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