Solved Exercises on Introduction to Time Video

Master time concepts with video timing: watching videos, timing activities, and basic time calculations through these 5 detailed exercises.

Solution: Exercises 1 to 3
1 Video Timing
Exercise 1
If a video is 10 minutes long and you watch it for 3 minutes, how much time is left to finish the video?
Definition:

Video Duration: Total length of the video in minutes

Time calculation method:
  1. Identify the total duration
  2. Identify the time watched
  3. Subtract watched time from total duration
Total Time
10 minutes
Watched
3 minutes
7 minutes
Step 1: Identify the total video length

The video is 10 minutes long

Step 2: Identify how much time you watched

You watched for 3 minutes

Step 3: Calculate remaining time

10 minutes - 3 minutes = 7 minutes

Time Remaining = 7 minutes
Final answer:

There are 7 minutes left to finish the video

Applied rules:

• Subtraction: Total - Watched = Remaining

• Time Calculation: Keep track of units (minutes)

• Video Duration: Total length of the video

Key Note: Always subtract the watched time from the total time.
Common Mistake: Don't add watched time to total time.
0:00
1:00
2:00
3:00
4:00
5:00
6:00
7:00
8:00
9:00
10:00
2 Movie Time Calculation
Exercise 2
If a movie starts at 2:00 PM and is 1 hour and 30 minutes long, what time does it end?
Definition:

Time Addition: Adding duration to a starting time

Start Time
2:00 PM
Duration
1h 30m
End Time
3:30 PM
Step 1: Identify the start time

The movie starts at 2:00 PM

Step 2: Identify the duration

The movie is 1 hour and 30 minutes long

Step 3: Add the duration to start time

2:00 PM + 1 hour = 3:00 PM

3:00 PM + 30 minutes = 3:30 PM

End Time = 3:30 PM
Final answer:

The movie ends at 3:30 PM

Applied rules:

• Time Addition: Start time + Duration = End time

• AM/PM: 2:00 PM to 3:30 PM remains PM

• Duration Breakdown: 1h 30m = 90 minutes

Key Note: Add hours first, then minutes.
Important: Be careful when crossing 12:00 (noon/midnight).
2:00 PM
2:30 PM
3:00 PM
3:30 PM
3 TV Show Timing
Exercise 3
If you watched 3 episodes of a show, and each episode is 20 minutes long, how long did you watch TV?
Definition:

Multiplication: Repeated addition of the same number

Episodes
3
Duration
20 minutes
Total
60 minutes
Step 1: Identify the number of episodes

You watched 3 episodes

Step 2: Identify the duration of each episode

Each episode is 20 minutes long

Step 3: Multiply to find total time

3 episodes × 20 minutes = 60 minutes

Step 4: Convert to hours if needed

60 minutes = 1 hour

Total Watching Time = 1 hour
Final answer:

You watched TV for 1 hour (60 minutes)

Applied rules:

• Multiplication: Number of items × Duration = Total

• Time Conversion: 60 minutes = 1 hour

• Repeated Addition: 20 + 20 + 20 = 60

Key Note: You can also add the same number repeatedly.
Important: Always check your units (minutes vs hours).
Episode 1: 0-20m
Episode 2: 20-40m
Episode 3: 40-60m
Time Video Concepts
Total Time = Episodes × Duration
TV Show Calculation
Concept 1
Start + Duration = End
Time Addition
Concept 2
Total - Watched = Remaining
Time Subtraction
Concept 3
Episodes × Duration = Total
Time Multiplication
Key definitions:

Video Duration: Total length of a video or show

Start Time: When the video begins

End Time: When the video finishes

Watching Time: How long you spent watching

Time calculation methods:
  1. Addition: Start time + Duration = End time
  2. Subtraction: Total - Watched = Remaining
  3. Multiplication: Episodes × Duration = Total time
  4. Conversion: Minutes to hours and vice versa
Common errors: Forgetting to convert units, mixing up addition and subtraction, not keeping track of AM/PM.
Key insight: Time always moves forward and needs to be calculated carefully.
Solution: Exercises 4 to 5
4 Video Pause Timing
Exercise 4
If a video is 25 minutes long and you paused it at 15 minutes, how much time is left after pausing?
Definition:

Pause Time: The point at which you stopped watching

Total Video
25 minutes
Paused At
15 minutes
Remaining
10 minutes
Step 1: Identify the total video length

The video is 25 minutes long

Step 2: Identify the pause time

You paused at 15 minutes

Step 3: Calculate remaining time

25 minutes - 15 minutes = 10 minutes

Step 4: Verify the calculation

15 minutes watched + 10 minutes remaining = 25 minutes total ✓

Time Left = 10 minutes
Final answer:

There are 10 minutes left after pausing at 15 minutes

Applied rules:

• Subtraction: Total - Paused at = Remaining

• Time Calculation: Keep units consistent

• Verification: Add parts to check total

Key Note: Pause time is the same as how much you've watched.
Important: The pause time is not subtracted from the total.
0:00
5:00
10:00
15:00 (PAUSED)
20:00
25:00
5 Multiple Videos Timing
Exercise 5
If you watched 4 videos that are each 15 minutes long, how much total time did you spend watching?
Definition:

Total Watching Time: Sum of time spent watching multiple videos

Videos
4
Duration
15 minutes
Total
60 minutes
Step 1: Identify the number of videos

You watched 4 videos

Step 2: Identify the duration of each video

Each video is 15 minutes long

Step 3: Multiply to find total time

4 videos × 15 minutes = 60 minutes

Step 4: Convert to hours if needed

60 minutes = 1 hour

Step 5: Alternative calculation

15 + 15 + 15 + 15 = 60 minutes

Total Watching Time = 1 hour
Final answer:

You spent 1 hour (60 minutes) watching videos

Applied rules:

• Multiplication: Number of items × Duration = Total

• Time Conversion: 60 minutes = 1 hour

• Repeated Addition: Same as multiplication

Key Note: 4 × 15 = 60, which is exactly 1 hour.
Important: You can multiply or add - both give the same result.
Video 1: 0-15m
Video 2: 15-30m
Video 3: 30-45m
Video 4: 45-60m
Time Video Concepts Summary
Start + Duration = End
Time Addition Formula
Key definitions:

Video Duration: Total length of a video or show

Start Time: When the video begins

End Time: When the video finishes

Watching Time: How long you spent watching

Remaining Time: How much is left to watch

Pause Time: The point where you stopped watching

Time calculation methods:
  1. Time Addition: Start + Duration = End
  2. Time Subtraction: Total - Watched = Remaining
  3. Time Multiplication: Episodes × Duration = Total
  4. Time Conversion: Minutes ↔ Hours
Tip 1: Always keep track of your units (minutes vs hours).
Tip 2: Remember: 60 minutes = 1 hour.
Tip 3: Check your work by adding parts to see if they equal the whole.
Tip 4: Use multiplication for repeated additions (same duration videos).
Common errors: Forgetting AM/PM changes, mixing up addition and subtraction, not converting units properly.
Memorization aids: Start + Duration = End, Total - Watched = Remaining, Episodes × Duration = Total.
Essential time calculation formulas:

• End Time: Start + Duration

• Remaining Time: Total - Watched

• Total Time: Number × Duration

• Time Conversion: 60 minutes = 1 hour

• Verification: Parts should add to equal the whole

Questions & Answers

Question: I get confused when adding time that goes past the hour. Like if a show starts at 2:45 PM and is 30 minutes long, what time does it end?

Answer: Great question! Here's how to handle time that crosses the hour:

  • Start at 2:45 PM
  • Add 15 minutes to reach 3:00 PM
  • Have 15 minutes left from the 30-minute show
  • Add remaining 15 minutes to 3:00 PM = 3:15 PM

So 2:45 PM + 30 minutes = 3:15 PM

Think of it as filling up the current hour first, then going into the next hour!

Question: Why do we say there are 60 minutes in an hour instead of 100 or 50?

Answer: The 60-minute hour comes from ancient civilizations:

  • The ancient Babylonians used a base-60 (sexagesimal) number system
  • 60 has many divisors: 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60
  • This made dividing time into smaller parts easier for calculations

For example: 60 minutes can be evenly divided into halves (30), thirds (20), quarters (15), fifths (12), etc.

This system was adopted by astronomers and has been used for thousands of years.

The same base-60 system gives us 360 degrees in a circle!

Question: How do I know if I should multiply or add when calculating time for multiple videos?

Answer: Here's how to decide:

  • Multiply: When you have the same duration repeated (like 3 episodes × 20 minutes each)
  • Add: When you have different durations (like 15 minutes + 20 minutes + 25 minutes)
  • Same duration: Use multiplication (faster)
  • Different durations: Use addition

Example: 4 videos at 15 minutes each = 4 × 15 = 60 minutes

But: 1 video at 10 min + 1 video at 15 min = 10 + 15 = 25 minutes

Multiplication is just a shortcut for repeated addition!

Complete Summary: Introduction to Time Video

This comprehensive summary covers all essential concepts about time calculations with videos for Grade 1 students.

Key Definitions

Video Duration: Total length of a video or show

Start Time: When the video begins

End Time: When the video finishes

Watching Time: How long you spent watching

Remaining Time: How much is left to watch

Pause Time: The point where you stopped watching

Total Time: Combined duration of multiple videos

Core Rules and Principles

Time Addition: Start + Duration = End

Time Subtraction: Total - Watched = Remaining

Time Multiplication: Episodes × Duration = Total

Time Conversion: 60 minutes = 1 hour

Base-60 System: Ancient system still used today

Time Forward: Time always moves forward

Step-by-Step Methods

Video Timing:

  1. Identify the total duration
  2. Identify the time watched
  3. Subtract to find remaining time

Time Addition:

  1. Identify the start time
  2. Identify the duration
  3. Add duration to start time
Examples and Applications

Simple Examples:

• 10 minutes - 3 minutes = 7 minutes remaining

• 2:00 PM + 1h 30m = 3:30 PM

• 3 episodes × 20 minutes = 60 minutes

Advanced Examples:

• 2:45 PM + 30 minutes = 3:15 PM

• 4 videos × 15 minutes = 60 minutes = 1 hour

• 25 minutes - 15 minutes = 10 minutes remaining

Real-Life Applications:

• Planning TV watching time

• Scheduling video lessons

• Managing screen time

• Planning movie nights

Tips and Common Pitfalls

Helpful Tips:

• Always check your units (minutes vs hours)

• Use multiplication for repeated additions

• 60 minutes = 1 hour

Common Mistakes:

• Adding watched time instead of subtracting

• Forgetting to convert units

• Mixing up addition and subtraction

• Not keeping track of AM/PM

Memory Aids:

• "Start + Duration = End"

• "Total - Watched = Remaining"

• "60 minutes makes 1 hour"

Key Takeaways

Essential Knowledge:

• Time calculations help manage video watching

• Video duration is the total length

• Time always moves forward

Skills to Master:

• Adding time to find end times

• Subtracting to find remaining time

• Multiplying for repeated durations

• Converting between minutes and hours

Why Time Matters:

• Helps manage screen time

• Essential for scheduling

• Foundation for advanced math

• Useful for daily planning