Grade 6
Mathematics
Unit: 08 Lesson: 01
Notes ─Elapsed Time KEY
Definition
Elapsed time is the amount of time between a start time and an end time.
John’s best marathon running time was 5 hours, 25 minutes, and 43 seconds.
His second best running time took 4 minutes and 24 seconds longer than his
best time. What was his second best running time?
Example 1
To answer, add 4 minutes and 24 seconds to 5 hours, 25 minutes, and 43 seconds.
5
h
+
5
h
25 min
43 sec
4
min
24 sec
29 min
67 sec
Add the hours, the minutes,
and the seconds
Convert 67 sec to 1 min 7 sec. Then add the 1 min 7 sec
as shown below.
5
h
29 min
1
+
5
h
min
7
sec
30 min
7
sec
Answer: His second best running time was 5 hours, 30
minutes, and 7 seconds.
Practice:
(1)
3 min 26 sec
(2) 6 h 29 min 9 sec
+ 1 min 47 sec
+ 3 h 43 min 32 sec
4 min 73 sec (convert 73 sec to 1 min 13 sec)
9 h 72 min 41 sec (convert 72 min to 1 h 12 min)
5 min 13 sec
10 h 12 min 41 sec
©2012, TESCCC
10/15/12
page 1 of 3
Grade 6
Mathematics
Unit: 08 Lesson: 01
Notes ─Elapsed Time KEY
Example 2
Sara gets up to go to school at 6:45 AM and arrives home
from school at 3:55 PM. How much time has passed since she
got up for school and arrived home from school?
Step 1: Use a table like the one below to organize the times. Make sure students label “AM” and “PM”
as necessary.
Start
6:45 AM
End
Hours
Minutes
7:45 AM
Step 2: Begin with the “Hours” column and add as many hours as you think necessary to get to the
“End” time. In the example, we started with 1 hours, and then added those hours to the start time in
the “Start” column. An “X” was placed in the “Minutes” column to show that no minutes had been
added.
Start
End
6:45 AM
7:45 AM
7:45 AM
10:45 AM
Hours
+1
Minutes
X
Step 3: Continue adding hours until no more hours can be added. Notice that when you cross the
“12:00” mark, the A.M. changes to PM.
Start
End
Hours
Minutes
6:45 AM
7:45 AM
+1
X
7:45 AM
10:45 AM
+3
X
10:45 AM
12:45 PM
+2
X
12:45 PM
3:45 PM
+3
X
3:45 PM
3:55 PM
Step 4: Since no more hours can be added without going past the end time, minutes must be added.
Add as many minutes as you think need to be added until you get to the end time.
©2012, TESCCC
Start
End
Hours
6:45 AM
7:45 AM
+1
X
7:45 AM
10:45 AM
+3
X
10:45 AM
12:45 PM
+2
X
12:45 PM
3:45 PM
3:45 PM
3:50 PM
3:50 PM
3:55 PM
+3
X
X
X
+5
+5
10/15/12
Minutes
page 2 of 3
Grade 6
Mathematics
Unit: 08 Lesson: 01
Notes ─Elapsed Time KEY
Step 5: Add the amounts in the “Hours” column and then the amounts in the “Minutes” column. This
total is the elapsed time.
Start
End
6:45 AM
7:45 AM
+1
X
7:45 AM
10:45 AM
+3
X
10:45 AM
12:45 PM
+2
X
12:45 PM
3:45 PM
3:45 PM
3:50 PM
3:50 PM
3:55 PM
+3
X
X
X
+5
+5
Elapsed Time
Hours
Minutes
9h
10 min
Solution: 9 hours and 10 minutes passed since Sara got up for school and arrived home from school.
Practice:
(1)
(2)
Find the elapsed time from 5:25 PM to 11:11 PM.
Start  End
Hours
Minutes
5:25 PM  8:25 PM
+3
X
8:25 PM  10:25 PM
+2
X
10:25 PM  10:30 PM
X
+5
10:30 PM  11:00 PM
X
+30
11:00 PM  11:11 PM
X
+11
Elapsed Time
5 hours
46 minutes
Find the elapsed time from 11:25 PM to 4:45 PM.
©2012, TESCCC
Start  End
Hours
Minutes
11:25 PM  12:25 AM
+1
X
12:25 AM  12:25 PM
+12
X
12:25 PM  4:25 PM
+4
X
4:25 PM  4:30 PM
X
+5
4:30 PM  4:45 PM
X
+15
Elapsed Time
17 hours
20 minutes
10/15/12
page 3 of 3