1. Elapsed Time A new way to calculate elapsed time

2. Pennsylvania State Math Standard  PA Math Standard 2.3.3.C  Anchor M3.B.1.1

3. 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?????

4. The T-Chart Method  To use the T-Chart method to figure out elapsed time, first draw a T-Chart like the one below:

5. 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.

6.  Next, add horizontal lines to your chart, and under the Minutes heading, list minutes in increments of 5, and stop at 55.

7.  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)

8.  When you have reached the stopping time, circle the time and the minutes listed on your T-Chart.

9.  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.

10. 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 T- Charts.  Let’s try this problem:  Ron sat down to draw at 5:10. He drew until 7:25. How long did Ron draw?

11. 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?

12.  Next, draw two T-Charts. On the first put the starting time, and Hours at the top.

13. 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?

14.  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.

15.  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?

16.  On your second T-Chart, write the time you reached after counting the hours (7:10) on the left. On the right, write Minutes.

17.  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.

18.  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.

19.  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.

20.  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.

21.  Let’s try another problem using analog clocks:  How much time has elapsed between the two clocks below?

22.  First, identify the times on each clock:

23.  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.

24.  Next, draw horizontal lines through your chart and list hours under the Hours column. How many hours do you think you’ll need?

25.  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.

26.  Now you can answer the first part of the question. The elapsed time is one hour and…

27.  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?

28.  Finally, add the correct times next to the corresponding minutes. Stop when you reach the ending time (4:15) Circle the time and minutes.

29.  You can now completely answer the question. The elapsed time is: One hour and 15 minutes

30. 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.

33. The T-Chart Method  You can practice finding elapsed time further using these websites:  http://www.shodor.org/interactivate/acti vities/ElapsedTime/ http://www.shodor.org/interactivate/acti vities/ElapsedTime/  http://www.free-training- tutorial.com/telling-time-games.html http://www.free-training- tutorial.com/telling-time-games.html  http://www.harcourtschool.com/activity/ elab2002/grade_3/018.html http://www.harcourtschool.com/activity/ elab2002/grade_3/018.html