Class 4 Maths - ICSE
Time
In the Class 4 ICSE Mathematics chapter on Time, students learn to read the clock accurately to the nearest minute using both 12-hour and 24-hour clock formats. This chapter covers essential skills such as converting between different units of time—including years, months, weeks, days, hours, minutes, and seconds—and calculating time intervals or elapsed time. Mastering these concepts is vital because time management is a crucial life skill, and questions from this chapter consistently appear in school examinations, carrying around 5 to 8 marks in the final ICSE math assessments through word problems and conversion sums.
Start Learning FreeKey Concepts
Reading the Clock
The short hand is the hour hand and the long hand is the minute hand, which moves in 5-minute intervals across the 12 numbers on the clock face.
AM and PM
AM stands for Ante Meridiem (midnight to noon) and PM stands for Post Meridiem (noon to midnight).
12-Hour vs 24-Hour Clock
The 24-hour clock uses four digits without AM or PM, where hours after noon are written as 13:00, 14:00, and so on up to 24:00.
Unit Conversion
Converting larger units of time to smaller ones (like hours to minutes by multiplying by 60) and smaller to larger units by dividing.
Addition and Subtraction of Time
Adding or subtracting hours and minutes separately, remembering to carry over 60 minutes as 1 hour.
Important Formulas
Board Exam Info
In ICSE Class 4 Mathematics question papers, the Time chapter typically carries about 5 to 8 marks. Common question types include converting hours to minutes, calculating the duration between two given times, word problems on elapsed time, and converting between 12-hour and 24-hour clock formats.
Frequently Asked Questions
How do I convert a 12-hour time in PM to a 24-hour time?
For any time from 1:00 PM to 11:59 PM, simply add 12 to the hour part and remove the letters PM (e.g., 3:30 PM becomes 15:30).
Why do we use 60 instead of 100 for time conversion?
Time is based on the sexagesimal (base-60) system inherited from ancient Babylonians, which is why there are 60 seconds in a minute and 60 minutes in an hour.
How do I calculate the time elapsed between 8:15 AM and 11:45 AM?
Subtract the starting hours and minutes from the ending hours and minutes. 11:45 minus 8:15 gives 3 hours and 30 minutes.
Learn Time with Your AI Tutor
10 different ways to study this chapter. Free for 3 chapters per day.
Lecture
Key Points
Interactive
Quiz
Flashcards