Elapsed time table: A table showing start times, end times, and the duration (elapsed time) between them.
- Identify the start time and end time
- Subtract the start time from the end time
- Handle borrowing when necessary
- Express the result in hours and minutes
| Activity | Start Time | End Time | Elapsed Time |
|---|---|---|---|
| Reading | 2:10 PM | 2:45 PM | 35 minutes |
| Homework | 3:30 PM | 4:15 PM | 45 minutes |
| Snack Time | 10:15 AM | 10:30 AM | 15 minutes |
| Recess | 11:00 AM | 11:30 AM | 30 minutes |
| Lunch | 12:00 PM | 12:35 PM | 35 minutes |
End: 2:45 PM, Start: 2:10 PM
45 - 10 = 35 minutes
End: 4:15 PM, Start: 3:30 PM
Need to borrow: 4:15 = 3:75
75 - 30 = 45 minutes
The elapsed time table is completed with all durations calculated.
• Same hour: When start and end times are in the same hour, subtract minutes directly
• Borrowing: When end minutes < start minutes, borrow 1 hour (60 minutes)
| Activity | Start Time | End Time | Elapsed Time |
|---|---|---|---|
| Reading | 2:10 PM | 2:45 PM | 35 min |
| Homework | 3:30 PM | 4:15 PM | 45 min |
| Snack Time | 10:15 AM | 10:30 AM | 15 min |
| Recess | 11:00 AM | 11:30 AM | 30 min |
| Lunch | 12:00 PM | 12:35 PM | 35 min |
Borrowing in elapsed time: When the minutes of the start time are greater than the minutes of the end time, borrow 1 hour (60 minutes) from the hour column.
| Activity | Start Time | End Time | Elapsed Time |
|---|---|---|---|
| Jogging | 6:55 AM | 7:20 AM | 25 minutes |
| Swimming | 9:40 AM | 10:15 AM | 35 minutes |
| Cycling | 3:50 PM | 4:25 PM | 35 minutes |
| Yoga | 5:35 PM | 6:10 PM | 35 minutes |
| Dancing | 7:25 PM | 8:00 PM | 35 minutes |
End: 7:20 AM, Start: 6:55 AM
Since 20 < 55, borrow 1 hour: 7:20 = 6:80
Minutes: 80 - 55 = 25 minutes
Hours: 6 - 6 = 0 hours
Total: 25 minutes
End: 10:15 AM, Start: 9:40 AM
Since 15 < 40, borrow 1 hour: 10:15 = 9:75
Minutes: 75 - 40 = 35 minutes
Hours: 9 - 9 = 0 hours
Total: 35 minutes
The elapsed time table is completed with all durations calculated using borrowing when necessary.
• Borrowing rule: When end minutes < start minutes, borrow 1 hour = 60 minutes
• Conversion: 1 hour = 60 minutes
| Activity | Start Time | End Time | Elapsed Time |
|---|---|---|---|
| Jogging | 6:55 AM | 7:20 AM | 25 min |
| Swimming | 9:40 AM | 10:15 AM | 35 min |
| Cycling | 3:50 PM | 4:25 PM | 35 min |
| Yoga | 5:35 PM | 6:10 PM | 35 min |
| Dancing | 7:25 PM | 8:00 PM | 35 min |
Multi-hour elapsed time: When the end time is in a different hour than the start time, subtract hours and minutes separately.
| Activity | Start Time | End Time | Elapsed Time |
|---|---|---|---|
| School Bus | 7:30 AM | 9:15 AM | 1 hr 45 min |
| Movie | 6:45 PM | 9:20 PM | 2 hrs 35 min |
| Field Trip | 10:25 AM | 2:10 PM | 3 hrs 45 min |
| Shopping | 1:15 PM | 4:00 PM | 2 hrs 45 min |
| Playground | 11:40 AM | 1:25 PM | 1 hr 45 min |
End: 9:15 AM, Start: 7:30 AM
Since 15 < 30, borrow 1 hour: 9:15 = 8:75
Minutes: 75 - 30 = 45 minutes
Hours: 8 - 7 = 1 hour
Total: 1 hour 45 minutes
End: 2:10 PM, Start: 10:25 AM
Convert to 24-hour: 2:10 PM = 14:10
Since 10 < 25, borrow 1 hour: 14:10 = 13:70
Minutes: 70 - 25 = 45 minutes
Hours: 13 - 10 = 3 hours
Total: 3 hours 45 minutes
The elapsed time table is completed with all durations calculated for multi-hour activities.
• Multi-hour subtraction: Handle hours and minutes separately
• Borrowing across hours: Same principle as single hour borrowing
• AM/PM conversion: Convert to 24-hour format for easier calculation
| Activity | Start Time | End Time | Elapsed Time |
|---|---|---|---|
| School Bus | 7:30 AM | 9:15 AM | 1 hr 45 min |
| Movie | 6:45 PM | 9:20 PM | 2 hrs 35 min |
| Field Trip | 10:25 AM | 2:10 PM | 3 hrs 45 min |
| Shopping | 1:15 PM | 4:00 PM | 2 hrs 45 min |
| Playground | 11:40 AM | 1:25 PM | 1 hr 45 min |
Elapsed time: The amount of time that passes between a start time and an end time
Start time: The time when an event begins
End time: The time when an event finishes
Elapsed time table: A table showing start times, end times, and the duration between them
Borrowing: Taking 1 hour (60 minutes) from the hour column when minutes need to be borrowed
- Identify start and end times: Locate them in the table
- Check for borrowing: If end minutes < start minutes, borrow 1 hour
- Perform subtraction: Subtract minutes and hours separately
- Combine results: Express as hours and minutes
- Fill the table: Enter the calculated elapsed time
• Always identify start and end times first
• Check if end minutes < start minutes (borrowing needed)
• When borrowing: reduce hours by 1, add 60 to minutes
• Subtract hours and minutes separately
• Fill table with consistent formatting
Crossing AM/PM boundary: When elapsed time spans from AM to PM (or vice versa).
| Activity | Start Time | End Time | Elapsed Time |
|---|---|---|---|
| Morning Class | 9:45 AM | 11:20 AM | 1 hr 35 min |
| Lunch Break | 12:00 PM | 12:45 PM | 45 min |
| Afternoon Class | 1:15 PM | 3:50 PM | 2 hrs 35 min |
| Study Session | 7:30 PM | 9:15 PM | 1 hr 45 min |
| Bedtime Story | 8:45 PM | 9:30 PM | 45 min |
End: 11:20 AM, Start: 9:45 AM
Since 20 < 45, borrow 1 hour: 11:20 = 10:80
Minutes: 80 - 45 = 35 minutes
Hours: 10 - 9 = 1 hour
Total: 1 hour 35 minutes
End: 3:50 PM, Start: 1:15 PM
Minutes: 50 - 15 = 35 minutes
Hours: 3 - 1 = 2 hours
Total: 2 hours 35 minutes
Check: 1:15 PM + 2 hrs 35 min = 1:15 + 2:35 = 3:50 PM ✓
The elapsed time table is completed with all durations calculated for activities spanning different time periods.
• AM/PM handling: Same calculation method regardless of AM/PM
• Verification: Add elapsed time to start time to confirm end time
| Activity | Start Time | End Time | Elapsed Time |
|---|---|---|---|
| Morning Class | 9:45 AM | 11:20 AM | 1 hr 35 min |
| Lunch Break | 12:00 PM | 12:45 PM | 45 min |
| Afternoon Class | 1:15 PM | 3:50 PM | 2 hrs 35 min |
| Study Session | 7:30 PM | 9:15 PM | 1 hr 45 min |
| Bedtime Story | 8:45 PM | 9:30 PM | 45 min |
Daily schedule table: An elapsed time table showing all activities in a day with their durations.
| Activity | Start Time | End Time | Elapsed Time |
|---|---|---|---|
| Wake Up | 7:00 AM | 7:15 AM | 15 min |
| Breakfast | 7:15 AM | 8:00 AM | 45 min |
| Travel to School | 8:00 AM | 8:45 AM | 45 min |
| School Day | 8:45 AM | 3:15 PM | 6 hrs 30 min |
| Travel Home | 3:15 PM | 4:00 PM | 45 min |
| Homework | 4:00 PM | 5:30 PM | 1 hr 30 min |
| Dinner | 6:00 PM | 6:45 PM | 45 min |
| Bedtime | 8:30 PM | 9:00 PM | 30 min |
| Total Time: | 12 hrs 15 min | ||
Wake Up: 7:15 - 7:00 = 15 min
Breakfast: 8:00 - 7:15 = 45 min
Travel to School: 8:45 - 8:00 = 45 min
End: 3:15 PM, Start: 8:45 AM
Convert to 24-hour: 3:15 PM = 15:15
Since 15 < 45, borrow 1 hour: 15:15 = 14:75
Minutes: 75 - 45 = 30 minutes
Hours: 14 - 8 = 6 hours
Total: 6 hours 30 minutes
Sum all elapsed times: 15min + 45min + 45min + 6hr30min + 45min + 1hr30min + 45min + 30min
Total: 12 hours 15 minutes
The daily schedule elapsed time table is completed with all durations calculated and a total of 12 hours 15 minutes.
• Total calculation: Add all elapsed times to find the total duration
• Consistency: Use the same format throughout the table
| Activity | Start Time | End Time | Elapsed Time |
|---|---|---|---|
| Wake Up | 7:00 AM | 7:15 AM | 15 min |
| Breakfast | 7:15 AM | 8:00 AM | 45 min |
| Travel to School | 8:00 AM | 8:45 AM | 45 min |
| School Day | 8:45 AM | 3:15 PM | 6 hrs 30 min |
| Travel Home | 3:15 PM | 4:00 PM | 45 min |
| Homework | 4:00 PM | 5:30 PM | 1 hr 30 min |
| Dinner | 6:00 PM | 6:45 PM | 45 min |
| Bedtime | 8:30 PM | 9:00 PM | 30 min |
| Total Time: | 12 hrs 15 min | ||
Elapsed time: The amount of time that passes between a start time and an end time
Start time: The time when an event begins
End time: The time when an event finishes
Elapsed time table: A table showing start times, end times, and the duration between them
Borrowing: Taking 1 hour (60 minutes) from the hour column when minutes need to be borrowed
24-hour format: Converting AM/PM times to 0-23 hour format for easier calculation
- Identify start and end times: Locate them in the table
- Check for borrowing: If end minutes < start minutes, borrow 1 hour
- Perform subtraction: Subtract minutes and hours separately
- Combine results: Express as hours and minutes
- Fill the table: Enter the calculated elapsed time
- Verify answers: Add elapsed time to start time to check end time
• Basic formula: Elapsed time = End time - Start time
• Borrowing rule: When end minutes < start minutes, borrow 1 hour (60 minutes)
• Same hour: Subtract minutes directly when in same hour
• Conversion: 1 hour = 60 minutes
• Verification: Start time + Elapsed time = End time
• Table format: Consistent presentation for clarity
Questions & Answers
Question: Why do I need to borrow when doing elapsed time subtraction?
Answer: You need to borrow when the minutes of your start time are greater than the minutes of your end time. For example, if you're going from 2:15 to 3:05:
- You can't subtract 15 from 5 (5 - 15 doesn't work)
- So you borrow 1 hour from the hour column (3:05 becomes 2:65)
- Now you can subtract: 65 - 15 = 50 minutes, and 2 - 2 = 0 hours
- The answer is 50 minutes
Borrowing makes the subtraction possible, just like in regular math!
Question: How can I help my child understand elapsed time tables?
Answer: Here are effective strategies to teach elapsed time tables:
- Use real analog clocks to show how time progresses visually
- Practice with simple examples first: 1:00 to 1:20, then 12:55 to 1:10
- Emphasize that borrowing means taking 60 minutes from the hour column
- Create daily schedule charts to make the concept practical
- Use manipulatives like paper clocks or time strips
Visual aids and real-life applications make the concept more meaningful!
Question: What if I have to subtract across AM and PM? Like from 11:45 AM to 1:15 PM?
Answer: For times that cross AM/PM, it's often easier to convert to 24-hour format:
- 11:45 AM stays 11:45
- 1:15 PM becomes 13:15 (add 12 hours)
- Now subtract: 13:15 - 11:45
- Since 15 < 45, borrow: 13:15 becomes 12:75
- Subtract: 75 - 45 = 30 minutes, 12 - 11 = 1 hour
- Answer: 1 hour and 30 minutes
Converting to 24-hour format eliminates the AM/PM complexity!