Elapsed Time (Grade 3)
Elapsed time is the amount of time that passes between a start time and an end time. In Class 3 Maths, students learn to find how much time has passed during an activity, a journey, or an event.
Knowing how to calculate elapsed time helps in planning daily activities such as school hours, travel, cooking, and play time. This topic builds on reading a clock and understanding hours and minutes.
What is Elapsed Time - Class 3 Maths (Time)?
Elapsed time is the difference between the end time and the start time of an event.
Elapsed Time = End Time − Start Time
Elapsed time can be measured in hours, minutes, or both. When we say "the movie lasted 2 hours and 15 minutes," we are describing elapsed time.
Types and Properties
There are three types of elapsed time problems in Class 3:
- Finding elapsed time: Given start time and end time, find how much time passed.
- Finding end time: Given start time and elapsed time, find the end time.
- Finding start time: Given end time and elapsed time, find the start time.
Method to find elapsed time — Counting forward:
- Start at the start time on a clock or number line.
- Count forward in hours first.
- Then count forward the remaining minutes.
- Add hours and minutes together.
Solved Examples
Example 1: Finding Elapsed Time (Hours Only)
Question: Ria's painting class starts at 3:00 PM and ends at 5:00 PM. How long is the class?
Think:
- Start time = 3:00 PM
- End time = 5:00 PM
- Count: 3:00 → 4:00 → 5:00 = 2 hours
Answer: The painting class is 2 hours long.
Example 2: Finding Elapsed Time (Hours and Minutes)
Question: Aman starts his homework at 4:15 PM and finishes at 5:45 PM. How much time did he spend?
Think:
- From 4:15 to 5:15 = 1 hour
- From 5:15 to 5:45 = 30 minutes
- Total = 1 hour 30 minutes
Answer: Aman spent 1 hour 30 minutes on homework.
Example 3: Finding Elapsed Time (Minutes Only)
Question: Priya starts eating lunch at 12:30 PM and finishes at 12:55 PM. How many minutes did she take?
Think:
- Start = 12:30, End = 12:55
- 55 − 30 = 25 minutes
Answer: Priya took 25 minutes to eat lunch.
Example 4: Finding the End Time
Question: Dev starts watching a cricket match at 2:00 PM. The match lasts 3 hours 30 minutes. When does it end?
Think:
- Start = 2:00 PM
- Add 3 hours → 5:00 PM
- Add 30 minutes → 5:30 PM
Answer: The match ends at 5:30 PM.
Example 5: Finding the Start Time
Question: Meera reached school at 8:30 AM. Her auto-rickshaw ride was 45 minutes. When did she leave home?
Think:
- End time = 8:30 AM
- Go back 45 minutes from 8:30
- 8:30 − 30 min = 8:00 AM
- 8:00 − 15 min = 7:45 AM
Answer: Meera left home at 7:45 AM.
Example 6: Elapsed Time Across Hours
Question: Kavi's art class starts at 10:40 AM and ends at 12:10 PM. How long is the class?
Think:
- From 10:40 to 11:40 = 1 hour
- From 11:40 to 12:10 = 30 minutes
- Total = 1 hour 30 minutes
Answer: The art class is 1 hour 30 minutes long.
Example 7: Using a Number Line
Question: Arjun starts playing at 4:20 PM and stops at 5:05 PM. How long did he play?
Think:
4:20 —(+40 min)→ 5:00 —(+5 min)→ 5:05
- 40 + 5 = 45 minutes
Answer: Arjun played for 45 minutes.
Example 8: Elapsed Time Word Problem
Question: Neha's school starts at 8:00 AM. Lunch break is at 12:30 PM. How many hours and minutes pass between school starting and lunch?
Think:
- From 8:00 to 12:00 = 4 hours
- From 12:00 to 12:30 = 30 minutes
- Total = 4 hours 30 minutes
Answer: 4 hours 30 minutes pass between school start and lunch.
Example 9: Finding End Time with Minutes Crossing the Hour
Question: Aditi starts reading at 6:50 PM. She reads for 35 minutes. When does she stop?
Think:
- Start = 6:50 PM
- 6:50 + 10 min = 7:00 PM
- 7:00 + 25 min = 7:25 PM
Answer: Aditi stops reading at 7:25 PM.
Key Points to Remember
- Elapsed time is the time that passes from start to end of an event.
- Use the formula: Elapsed Time = End Time − Start Time.
- Count forward in hours first, then count the remaining minutes.
- To find end time, add the elapsed time to the start time.
- To find start time, subtract the elapsed time from the end time.
- A number line or clock face helps to count time that crosses the hour.
- Always check whether the answer is in AM or PM.
Practice Problems
- Rahul starts cycling at 5:15 PM and returns at 6:00 PM. How long did he cycle?
- A train departs at 9:30 AM and arrives at 11:45 AM. Find the elapsed time.
- Priya starts cooking at 6:00 PM. She takes 1 hour 20 minutes. When does she finish?
- A movie ends at 8:30 PM. It was 2 hours 15 minutes long. When did it start?
- Aman's school starts at 7:45 AM and ends at 1:30 PM. How long is the school day?
- Meera starts drawing at 3:50 PM and draws for 40 minutes. When does she stop?
- The library opens at 10:00 AM. Kavi visits for 1 hour 45 minutes. When does he leave?
Frequently Asked Questions
Q1. What is elapsed time?
Elapsed time is the amount of time that passes between the start and end of an event. It is found by subtracting the start time from the end time.
Q2. How do you find elapsed time in Class 3?
Count forward from the start time to the end time. First count the full hours, then count the remaining minutes. Add them together to get the elapsed time.
Q3. What is the formula for elapsed time?
Elapsed Time = End Time minus Start Time. For example, if an event starts at 2:00 PM and ends at 4:30 PM, the elapsed time is 2 hours 30 minutes.
Q4. How do you find end time from elapsed time?
Add the elapsed time to the start time. For example, if you start at 3:00 PM and the activity takes 1 hour 45 minutes, the end time is 4:45 PM.
Q5. How do you find start time from elapsed time?
Subtract the elapsed time from the end time. For example, if an event ends at 5:00 PM and lasted 2 hours, the start time was 3:00 PM.
Q6. What tools help in finding elapsed time?
A clock face and a number line are helpful tools. Draw a number line, mark the start and end times, and count forward in hour and minute jumps.
Q7. What is the difference between elapsed time and clock time?
Clock time tells the current time (e.g., 3:15 PM). Elapsed time tells how much time has passed between two clock times (e.g., 2 hours 30 minutes).
Q8. Can elapsed time be more than 12 hours?
Yes. For example, if an event starts at 8:00 AM and ends at 9:00 PM the same day, the elapsed time is 13 hours. In Class 3, most problems stay within a few hours.
Q9. Is elapsed time covered in the NCERT Class 3 syllabus?
Yes. Elapsed time is part of the Time chapter in Class 3 NCERT Maths. Students learn to calculate the duration of events using hours and minutes.
