Mathematics Class 5 - Time Notes

Time

Welcome to the chapter on Time for Class 5. In this chapter, you will learn how to read clocks, understand units of time, convert between hours, minutes, and seconds, and solve word problems related to time. By the end of this chapter, you will be able to use time in daily life and solve time-based questions confidently!

Introduction

Time helps us know when things happen. We use clocks and watches to read time. Time is measured in hours, minutes, and seconds. Let’s learn how to read and use time!

Units of Time

• Second: The smallest unit of time.
• Minute: 1 minute = 60 seconds.
• Hour: 1 hour = 60 minutes.
• Day: 1 day = 24 hours.
• Week: 1 week = 7 days.
• Month: About 30 or 31 days.
• Year: 1 year = 12 months.

Reading a Clock

A clock has an hour hand, a minute hand, and sometimes a second hand. The hour hand is short, the minute hand is long, and the second hand is thin and moves quickly.

• When the minute hand is at 12, it is "o'clock".
• When the minute hand is at 6, it is "half past".
• When the minute hand is at 3, it is "quarter past".
• When the minute hand is at 9, it is "quarter to".

Example: If the hour hand is at 4 and the minute hand is at 6, it is 4:30 or half past 4.

Converting Units of Time

• To convert hours to minutes: multiply by 60.
• To convert minutes to seconds: multiply by 60.
• To convert minutes to hours: divide by 60.

Example: 2 hours = 2 × 60 = 120 minutes

Solving Word Problems

Use your knowledge of time to solve real-life problems. Read the question, find the time units, and solve.

• Example: If a movie starts at 5:15 PM and ends at 7:00 PM, how long is the movie? (7:00 - 5:15 = 1 hour 45 minutes)

Fun Activity: Time Challenge!

Set a timer for 2 minutes. See how many jumping jacks you can do before the time is up!

Summary

• Time is measured in seconds, minutes, hours, days, weeks, months, and years.
• Learn to read clocks and convert between units of time.
• Practice word problems to use time in real life.

Practice Questions

1. How many minutes are there in 3 hours?
2. What time is it when the hour hand is at 7 and the minute hand is at 12?
3. Convert 120 seconds to minutes.
4. If school starts at 8:30 AM and ends at 2:30 PM, how many hours are you in school?
5. How many days are there in a week?

Challenge Yourself

• Make your own timetable for a day. Write the time for each activity.
• Solve: If a train leaves at 3:45 PM and reaches at 6:15 PM, how long is the journey?

Did You Know?

• There are 86,400 seconds in a day!
• The first clocks were made thousands of years ago using the sun.

Glossary

• Hour: 60 minutes.
• Minute: 60 seconds.
• Second: The smallest unit of time.
• Timetable: A plan that shows times for activities.

Answers to Practice Questions

1. 180 minutes
2. 7 o'clock
3. 2 minutes
4. 6 hours
5. 7 days

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Practice reading clocks and solving time problems to become a time expert!