Solved Exercises on Exercise Time Lapse in Grade 3

Master exercise time calculations: understanding workout durations, rest periods, and elapsed time during physical activities through these 5 detailed exercises.

Solution: Exercises 1 to 3
1 Basic Exercise Time Calculation
Exercise 1
Tom started jogging at 7:00 AM and finished at 7:45 AM. How much time did Tom spend jogging?
Definition:

Exercise Time Lapse: The total duration of time spent doing an exercise, calculated from the start time to the end time.

Exercise Time Calculation Method:
  1. Identify the start time and end time of the exercise
  2. Count the minutes between start and end
  3. Convert to hours and minutes if necessary
  4. State the total exercise time
Step 1: Identify start and end times

Start time: 7:00 AM, End time: 7:45 AM

Step 2: Calculate the minutes

From 7:00 AM to 7:45 AM = 45 minutes

Step 3: State the total time

Tom jogged for 45 minutes

Tom jogged for 45 minutes
Final answer:

Tom spent 45 minutes jogging from 7:00 AM to 7:45 AM.

Applied rules:

• Time Subtraction: End time - Start time = Exercise duration

• Minute Counting: Count minutes when hours are the same

• Duration Calculation: Total time spent on the activity

2 Exercise Time Across Hours
Exercise 2
Sarah's yoga session started at 6:30 AM and ended at 7:15 AM. How long was her yoga session?
Definition:

Crossing the Hour: When calculating time that goes past the next hour mark, break the calculation into two parts: before and after the hour.

Step 1: Identify the time periods

Before 7:00 AM: 6:30 AM to 7:00 AM
After 7:00 AM: 7:00 AM to 7:15 AM

Step 2: Calculate time before 7:00 AM

From 6:30 AM to 7:00 AM = 30 minutes

Step 3: Calculate time after 7:00 AM

From 7:00 AM to 7:15 AM = 15 minutes

Step 4: Add the two periods together

30 minutes + 15 minutes = 45 minutes

Yoga session lasted 45 minutes
Final answer:

Sarah's yoga session lasted 45 minutes from 6:30 AM to 7:15 AM.

Applied rules:

• Breaking at Hour: Split time calculations at the next hour mark

• Minute Calculation: Count minutes to the next hour, then minutes after

• Sequential Addition: Add separate time periods to get total time

3 Multiple Exercise Periods
Exercise 3
Marcus did jumping jacks for 10 minutes, took a 5-minute break, then did push-ups for 15 minutes. What was the total time for his exercise routine?
Definition:

Multiple Exercise Periods: Calculating total time across multiple exercise sessions and rest periods.

Step 1: Identify each time period

Jumping jacks: 10 minutes
Break: 5 minutes
Push-ups: 15 minutes

Step 2: Add all time periods together

10 minutes (jumping jacks) + 5 minutes (break) + 15 minutes (push-ups) = 30 minutes

Step 3: State the total time

Total exercise routine time = 30 minutes

Total exercise routine: 30 minutes
Final answer:

Marcus's total exercise routine took 30 minutes including both exercise periods and the break.

Applied rules:

• Individual Calculation: Calculate each activity time separately

• Break Inclusion: Include rest periods in total time

• Total Time: Add all individual times together

Exercise Time Lapse Rules and Methods
Exercise Duration = End Time - Start Time
Time Calculation Formula
Time Subtraction
End - Start = Duration
Calculate exercise time
Crossing Hour
Split at Next Hour
Calculate in two parts
Multiple Periods
Add All Periods
Total exercise time
Key Definitions:

Start Time: The beginning time of an exercise

End Time: The finishing time of an exercise

Exercise Duration: The total amount of time spent on an exercise

Basic Rule: Subtract the start time from the end time to find exercise duration.
Crossing Hours: Split calculations at the next hour mark for easier computation.
Multiple Activities: Add all exercise and rest periods for total time.
Tip 1: Use a number line to visualize exercise time passing from start to end.
Tip 2: When crossing an hour, count minutes to the next hour first.
Tip 3: Remember that 60 minutes equals 1 hour when converting.
Solution: Exercises 4 to 5
4 Exercise Schedule Planning
Exercise 4
A fitness routine includes 20 minutes of stretching, 30 minutes of cardio, and 15 minutes of strength training. If the routine starts at 6:00 AM, what time will it end? How much total exercise time is there?
Definition:

Exercise Schedule Planning: Calculating when a multi-part exercise routine will end based on its start time and duration.

Step 1: Calculate total exercise time

Stretching: 20 minutes
Cardio: 30 minutes
Strength training: 15 minutes
Total: 20 + 30 + 15 = 65 minutes

Step 2: Convert minutes to hours and minutes

65 minutes = 1 hour 5 minutes (since 65 ÷ 60 = 1 remainder 5)

Step 3: Add duration to start time

Start: 6:00 AM
Add: 1 hour → 7:00 AM
Add: 5 minutes → 7:05 AM

Step 4: Verify the calculation

From 6:00 AM to 7:00 AM = 60 minutes
From 7:00 AM to 7:05 AM = 5 minutes
Total: 60 + 5 = 65 minutes ✓

Routine ends at 7:05 AM, total time: 1 hour 5 minutes
Final answer:

The fitness routine will end at 7:05 AM. The total exercise time is 1 hour 5 minutes.

Applied rules:

• Time Addition: Add duration to start time to find end time

• Unit Conversion: 60 minutes = 1 hour

• Verification: Check by calculating elapsed time back

5 Exercise Intervals with Rest
Exercise 5
A workout plan has 3 rounds: 8 minutes of running followed by 2 minutes of rest. How much total time does the workout take? How much of that is actual exercise time versus rest time?
Definition:

Exercise Intervals: Calculating total time across repeated exercise and rest cycles.

Step 1: Calculate time for one round

Running: 8 minutes
Rest: 2 minutes
One round: 8 + 2 = 10 minutes

Step 2: Calculate total time for 3 rounds

One round: 10 minutes
Three rounds: 3 × 10 = 30 minutes

Step 3: Calculate total exercise time

Running per round: 8 minutes
Three rounds: 3 × 8 = 24 minutes

Step 4: Calculate total rest time

Rest per round: 2 minutes
Three rounds: 3 × 2 = 6 minutes

Total workout: 30 minutes, Exercise: 24 minutes, Rest: 6 minutes
Final answer:

The workout takes 30 minutes total: 24 minutes of actual exercise and 6 minutes of rest.

Applied rules:

• Multiplication: Multiply single round time by number of rounds

• Separation: Calculate exercise and rest time separately

• Total Time: Add all individual times together

Key Concepts: Exercise Time Lapse, Definitions, Methods, and Formulas
Exercise Duration = End Time - Start Time
Time Calculation Formula
Key definitions:

Exercise Time Lapse: The amount of time that passes between the start and end of an exercise

Start Time: The time when an exercise begins

End Time: The time when an exercise finishes

Complete methodology:
  1. Identify times: Find the start and end times of the exercise
  2. Check for crossing hours: If the time period goes past the next hour, split the calculation
  3. Calculate each period: Count the hours and minutes between times
  4. Add periods together: Combine all time periods for the total
Tip 1: Draw a timeline to visualize exercise time passing from start to end.
Tip 2: When crossing an hour, think of it as two separate time periods.
Tip 3: Remember that 12:00 AM is midnight, and 12:00 PM is noon.
Tip 4: Check your answer by adding the exercise time back to the start time.
Common errors: Forgetting to cross hours, incorrect minute calculations, miscounting hours.
Exercise planning: Practice with various time combinations, work on time management skills, understand AM/PM differences.
Formulas to know by heart:

• Basic Formula: Exercise Duration = End Time - Start Time

• Time Addition: Start Time + Duration = End Time

• Unit Conversion: 60 minutes = 1 hour

• Interval Calculation: Single Round Time × Number of Rounds = Total Time

Exercise with Visualization: Weekly Workout Plan
Exercise 6: Exercise Time Management
Weekly workout schedule:
Monday: Running 30 min
Tuesday: Swimming 45 min
Wednesday: Yoga 20 min
Thursday: Cycling 35 min
Friday: Strength Training 40 min
How much total exercise time is there in the week?

Analysis: Calculate the time for each activity and add them together.

  • Monday: Running = 30 minutes
  • Tuesday: Swimming = 45 minutes
  • Wednesday: Yoga = 20 minutes
  • Thursday: Cycling = 35 minutes
  • Friday: Strength Training = 40 minutes
  • Total: 30 + 45 + 20 + 35 + 40 = 170 minutes = 2 hours 50 minutes

Questions & Answers

Question: My 3rd grade students struggle with calculating exercise time when it crosses the hour. How can I help them understand this concept?

Answer: Here are helpful strategies for teaching time crossing the hour:

  • Visual approach: Show how the minute hand moves past 12 to the next hour
  • Break it down: Always split the calculation at the next hour mark
  • Count to the hour: First count minutes to reach the next hour, then count minutes after

Example: For 6:30 AM to 7:15 AM:

  • From 6:30 AM to 7:00 AM = 30 minutes
  • From 7:00 AM to 7:15 AM = 15 minutes
  • Total: 30 + 15 = 45 minutes

Use analog clocks to demonstrate the concept visually.

Question: My child gets confused about AM and PM when calculating exercise times. What strategies can help them?

Answer: Effective strategies for AM/PM understanding:

  • Memory aids: AM = "Morning" (ante meridiem), PM = "Afternoon/Eve" (post meridiem)
  • Daily routine connection: Link times to familiar activities
  • Visual timeline: Create a 24-hour timeline showing AM and PM

Examples:

  • AM: Wake up at 7:00 AM, lunch at 12:00 PM
  • PM: Dinner at 6:00 PM, bedtime at 8:00 PM

Practice with real exercise schedules to make the concept more relevant.

Question: How do I calculate total time when there are exercise and rest periods? Sometimes I don't know where to start.

Answer: To calculate total time with exercise and rest periods, follow these steps:

  1. List all periods: Write down each exercise and rest period
  2. Calculate each: Find the time for each activity
  3. Add them all: Add all the times together

Example: If you have 10 min exercise + 5 min rest + 15 min exercise:

  • Total: 10 + 5 + 15 = 30 minutes
  • Exercise time: 10 + 15 = 25 minutes
  • Rest time: 5 minutes

Remember: Total time includes both exercise and rest periods!

Question: What if I have to convert minutes to hours? Like if I get 95 minutes, how do I write it in hours and minutes?

Answer: To convert minutes to hours and minutes, divide by 60:

  • Divide by 60: The whole number is the hours
  • Remainder is minutes: What's left after dividing by 60

For 95 minutes:

  • 95 ÷ 60 = 1 remainder 35
  • So 95 minutes = 1 hour 35 minutes

More examples:

  • 120 minutes = 2 hours (120 ÷ 60 = 2 remainder 0)
  • 135 minutes = 2 hours 15 minutes (135 ÷ 60 = 2 remainder 15)
  • 180 minutes = 3 hours (180 ÷ 60 = 3 remainder 0)

Remember: Every 60 minutes equals 1 hour!

Question: How do I check if my answer is right? Sometimes I'm not sure about my calculations.

Answer: Here are effective ways to check your time calculations:

  • Add back method: Add your calculated time to the start time and see if you get the end time
  • Count forward: Starting from the start time, count forward by your answer
  • Estimate first: Before calculating, estimate if your answer makes sense

Example: If you calculate that 7:00 AM to 7:45 AM is 45 minutes:

  • Add back: 7:00 AM + 45 minutes = 7:45 AM ✓
  • Count forward: 7:00 → 7:45 = 45 minutes ✓

Always double-check by using a different method!