Elapsed
Time
A new way to calculate
elapsed time
Pennsylvania State
Math Standard
PA
Math Standard
2.3.3.C
Anchor M3.B.1.1
How do you figure out how much time has
passed, or how much time will pass during a
certain activity?
 Do




you…
Picture a clock in your head, and count
through the hours and minutes with your
fingers?
Actually look at a clock, and count through
the hours and minutes?
Take a guess?
Is there another way?????
The T-Chart Method
 To
use the T-Chart method to figure out
elapsed time, first draw a T-Chart like the
one below:
Let’s use the T-Chart to figure out this problem.



Brianna started her Algebra homework at 6:15. She finished at 6:50.
How long did it take her to complete her homework?
First, identify your starting time by circling or highlighting it. Next,
identify the ending time, and the question the problem is asking.
On your T-Chart, put the starting time on the left hand side, and since
we are only working with minutes this time ( We can see that it took
Brianna less than 1 hour to complete her homework) write Minutes on
the right hand side.
 Next,
add horizontal lines to your chart, and under
the Minutes heading, list minutes in increments of 5,
and stop at 55.
 Under
the left hand column where the starting time
is listed, continue listing the time in 5 minute
increments until you reach the stopping time (6:50)
 When
you have reached the stopping
time, circle the time and the minutes listed
on your T-Chart.
 Now


you can answer the question.
Brianna started her Algebra homework at 6:15. She finished
at 6:50. How long did it take her to complete her
homework?
It took Brianna 35 minutes to complete her homework.
The T-Chart Method
 You
can also use the T-Chart method to
figure out elapsed time that includes
hours and minutes by using 2 separate TCharts.
 Let’s try this problem:

Ron sat down to draw at 5:10. He drew until
7:25. How long did Ron draw?
The T-Chart Method
 First,
identify your starting time and end
time by circling or highlighting them.
 Next, identify what question the problem
is asking.

Ron sat down to draw at 5:10. He drew until
7:25. How long did Ron draw?
 Next,
draw two T-Charts. On the first put
the starting time, and Hours at the top.
As before, draw a few horizontal lines down
your T-Chart. Under hours, start listing hours
starting at 1. You can take a guess at how
many hours you will need to list. What do
you think?
 Next,
start listing the appropriate time next to each
hour. Stop when you are close to the stopping time,
but you have not gone past it.
 Circle the time where you should stop. Which time
listed below is close to the stopping time, but has
not passed it?
*Remember that the stopping time is 7:25.
 7:10
is close to the stopping time of 7:25,
but is not past it. 8:10 would be too long
because it went past the stopping time.
 So
now we can answer part of the
question. Ron drew for 2 hours. But how
many minutes?
 On
your second T-Chart, write the time
you reached after counting the hours
(7:10) on the left. On the right, write
Minutes.
 As
before, draw horizontal lines
down your chart, and list minutes in
increments of 5. Take a guess as to
how many minutes you will need. If
you need to add more minutes, you
can always go back to add more.
 Under
the left hand column, continue
listing the times in 5 minute increments
until you reach the stopping time. (7:25).
When you reach the stopping time, circle
it.
 Since
the stopping time is 7:25, as we
earlier identified, we can see that the
number of minutes Ron spent drawing
was 15 minutes.
 We

can now answer the entire question:
Ron sat down to draw at 5:10. He drew until
7:25. How long did Ron draw?
Ron drew for 2 hours and 15 minutes.
 Let’s
try another problem using analog
clocks:

How much time has elapsed between the
two clocks below?
 First,
identify the times on each clock:
 Next,
draw a T-Chart to figure out the time elapsed.
Has more than an hour gone by? Then you will
need 2 T-Charts.
 Set up the first T-Chart labeled with the starting time,
and Hours at the top.
 Next,
draw horizontal lines through your
chart and list hours under the Hours
column. How many hours do you think
you’ll need?
 Next,
list the appropriate times next to
each hour.
 Which time is close to the stopping time
(4:15) without going past it? Circle it.
 Now
you can answer the first part of the
question. The elapsed time is one hour
and…
 Now,
how many minutes have passed?
 Draw your T-Chart labeled with the time you
reached after finding the hours, (4:00) and
Minutes at the top.
 Draw the horizontal lines, and add minutes in
5 minute increments. Keep your stopping
time in mind…how many minutes do you
need to add?
 Finally,
add the correct times next to the
corresponding minutes. Stop when you
reach the ending time (4:15) Circle the
time and minutes.
 You
can now completely answer the question. The
elapsed time is:
One hour and 15 minutes
The T-Chart Method
 Try
finding the elapsed times using the
analog clocks on the following slides.
Create your own T-Charts to find the
answers.
The T-Chart Method
 You
can practice finding elapsed time
further using these websites:
 http://www.shodor.org/interactivate/acti
vities/ElapsedTime/
 http://www.free-trainingtutorial.com/telling-time-games.html
 http://www.harcourtschool.com/activity/
elab2002/grade_3/018.html