Understanding Elapsed Time

Today, we’re going to learn about elapsed time. Elapsed time is the amount of time that passes from the beginning of an event to the end of that event.

Key Concepts

  1. What is Elapsed Time?
    • When we talk about elapsed time, we are looking at how long something takes. For example, if you start homework at 4 PM and finish at 5 PM, the elapsed time is 1 hour.
  2. How to Calculate Elapsed Time
    • To find the elapsed time, you can subtract the start time from the end time.
    • If you have the same units (like hours and minutes), simply take one away from the other.

Example 1

  • Start Time: 2:30 PM
  • End Time: 3:15 PM

Step 1: Convert times to minutes if it helps.

  • 2:30 PM = 2 hours and 30 minutes = 150 minutes
  • 3:15 PM = 3 hours and 15 minutes = 195 minutes

Step 2: Subtract the start time from the end time.

  • 195 minutes – 150 minutes = 45 minutes

So, the elapsed time is 45 minutes.

Example 2

  • Start Time: 11:45 AM
  • End Time: 12:30 PM

Step 1: Just subtract the hours and minutes directly here.

  • From 11:45 AM to 12:00 PM is 15 minutes.
  • From 12:00 PM to 12:30 PM is 30 minutes.

Step 2: Add them up.

  • 15 minutes + 30 minutes = 45 minutes

The elapsed time is 45 minutes.

Key Rules

  • Count by Hours and Minutes: If you’re working with hours and minutes, always keep track of both.
  • Use a Number Line: Drawing a number line can help you visualise the time differences.
  • Be Careful with AM and PM: Make sure you know if the time is in the morning (AM) or evening (PM).

Tips and Tricks

  • Break It Down: If the time spans over lunch or dinner, break it into parts.
  • Practice with Clocks: Use a clock to practice reading times and figuring out the elapsed time.
  • Use Timers: Set a timer for various activities and then check how long they take to get a feel for elapsed time.

Questions on Elapsed Time

Easy Level Questions

  1. If you start watching a movie at 6:00 PM and finish at 7:30 PM, how long was the movie?
  2. You begin reading at 4:15 PM and stop at 5:00 PM. How long did you read for?
  3. A train leaves the station at 9:00 AM and arrives at 10:15 AM. What is the elapsed time?
  4. If you play a game from 3:30 PM to 4:00 PM, how long did you play?
  5. You have a meeting from 1:00 PM to 2:00 PM. What is the duration of the meeting?
  6. Your favourite show starts at 8:00 PM and ends at 8:30 PM. How long is the show?
  7. You walk the dog from 5:10 PM to 5:40 PM. How long did you walk the dog?
  8. If your class starts at 2:15 PM and ends at 3:00 PM, how long is the class?
  9. A concert begins at 7:00 PM and ends at 9:00 PM. What is the elapsed time?
  10. You bake cookies from 4:00 PM to 5:15 PM. How long were they in the oven?

Medium Level Questions

  1. You start homework at 5:25 PM and finish at 6:40 PM. What is the elapsed time?
  2. A football match starts at 3:15 PM and ends at 4:45 PM. How long is the match?
  3. You go to the gym from 12:30 PM to 1:45 PM. How long do you spend at the gym?
  4. If your favourite cartoon is on from 10:00 AM to 10:30 AM and then again from 11:00 AM to 11:30 AM, what is the total time spent watching?
  5. A bus leaves at 4:50 PM and arrives at 5:30 PM. What is the travel time?
  6. You start a puzzle at 2:05 PM and finish it at 3:15 PM. How long did you work on the puzzle?
  7. If you start cooking at 6:20 PM and finish at 6:55 PM, how long did you cook?
  8. A movie starts at 8:15 PM and finishes at 10:00 PM. What is the duration of the movie?
  9. You begin studying at 5:00 PM and stop at 6:10 PM. How much time did you study?
  10. If your class runs from 9:10 AM to 10:05 AM, how long is the class?

Hard Level Questions

  1. A train departs at 8:45 AM and arrives at 10:30 AM. Calculate the elapsed time.
  2. You start a book at 3:22 PM and finish at 4:45 PM. How long did you spend reading?
  3. A game starts at 7:15 PM and ends at 9:00 PM. What is the elapsed time in hours and minutes?
  4. If you start a project at 1:05 PM and finish at 3:25 PM, how long did it take?
  5. You watch a series of three episodes back-to-back: 4:00 PM to 5:00 PM, 5:10 PM to 6:00 PM, and 6:10 PM to 7:00 PM. What is the total time spent watching?
  6. A car trip starts at 11:30 AM and ends at 1:15 PM. What is the duration of the trip?
  7. You begin a workout at 6:15 PM and end at 7:50 PM. How long is your workout?
  8. A lecture runs from 9:45 AM to 11:15 AM. What is the elapsed time?
  9. If you start baking at 2:30 PM and finish at 4:00 PM, how long did you bake?
  10. You play a video game from 5:05 PM to 5:50 PM, then take a break and play again from 6:15 PM to 7:00 PM. What is the total time spent playing?

Answers to Questions

Easy Level Answers

  1. 1 hour 30 minutes
  2. 45 minutes
  3. 1 hour 15 minutes
  4. 30 minutes
  5. 1 hour
  6. 30 minutes
  7. 30 minutes
  8. 45 minutes
  9. 2 hours
  10. 1 hour 15 minutes

Medium Level Answers

  1. 1 hour 15 minutes
  2. 1 hour 30 minutes
  3. 1 hour 15 minutes
  4. 1 hour
  5. 40 minutes
  6. 1 hour 10 minutes
  7. 35 minutes
  8. 1 hour 45 minutes
  9. 1 hour 10 minutes
  10. 55 minutes

Hard Level Answers

  1. 1 hour 45 minutes
  2. 1 hour 23 minutes
  3. 1 hour 45 minutes
  4. 2 hours 20 minutes
  5. 2 hours 40 minutes
  6. 1 hour 45 minutes
  7. 1 hour 35 minutes
  8. 1 hour 30 minutes
  9. 1 hour 30 minutes
  10. 1 hour 30 minutes

That’s all for today’s lesson on elapsed time! Remember to practice, and soon you’ll be a pro at calculating how long things take.