Elapsed Time

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Elapsed Time
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Finding Elapsed Time
Given a starting time and an ending time, find
out how much time was spent. Given a start time
and the amount of time spent, tell the finishing
time. Given an ending time and the amount of
time spent, tell the starting time.
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KEY POINTS TO REMEMBER

• You need to understand the difference between
  A.M. and P.M.
• There are only 60 minutes in an hour. Therefore,
  using addition wont always work, you have to
  think it through.

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Midnight starts a new day

• 1200 A.M. midnight is the beginning of each new
  day
• You probably get up around 700 A.M.
• 1030 or 1100 A.M. you are thinking about lunch
• 1200 P.M. IS NOON
• After noon is PAST MORNING

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Is it A.M. or P.M.?
PTA Meeting
PM
Getting Ready for School
AM
Getting Ready for Bed
PM
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Is it A.M. or P.M.?
School Gets Out
PM
AM
The Sun Rises
Softball Game
PM
Stars In The Sky
PM
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Each number on a clock represents 5 minutes.
Replacing the numbers with multiples of 5 will
help you see why there are 60 minutes in an hour.
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60
Each number on a clock represents 5 minutes.
Replacing the numbers with multiples of 5 will
help you see why there are 60 minutes in an hour.
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55
50
10
45
15
40
20
25
35
30
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What time will it be 1 hour later?
417 PM
317 PM
1253 AM
1153 PM
843 PM
743 PM
251 PM
351 PM
EASY PATTERN
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What time will it be15 minutes later?
If we add 15 minutes to the two minutes we have,
the time will be 917
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What time will it be15 minutes later?
If we add 15 minutes to the 55 minutes we have,
the time will be 870 Only 60 minutes in an hour
Simply adding will not work.
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What time will it be15 minutes later?
In 5 minutes it will be 900. We still have 10
more minutes In 10 more minutes, it will be 910
or ten minutes after 9
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What time will it be 15 minutes later?
332 PM
317 PM
12 08 AM
1153 PM
8 02 PM
747 PM
306 PM
251 PM
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Lets Try Something More Challenging
What time will it be in 2 hours 7 min.
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What time will it be 2 hours 7 minutes later?
What time will it be in 2 hours? 1102 Now add 7
min. That makes the time 1109
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What time will it be 2 hours and 7 minutes later?
524 PM
317 PM
1258 PM
1051 AM
950 AM
743 AM
251 PM
458 PM
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Time Word Problems

• Janice started reading a great book at 613pm.
  She finished at 928pm. How long did she spend
  reading?
• HINT Count up the hours and then the minutes.
• 713, 813, 913 3 hours
• From 913 to 928 is 15 minutes

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Time Word Problems

• Brooke left home to visit her grandmother at 713
  a.m. Her bike ride lasted 18 minutes. What time
  did she arrive?
• HINT If it had taken 20 minutes she would have
  arrived at 733, count back 2 minutes
• After 10 minutes it is 723
• After 10 more minutes it would be 733
• Take two minutes away, and it is 731

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Time Word Problems

• Students arrive at school at 830 a.m. They get
  back on the buses around 315p.m. How long is
  the school day?
• Lets take is step by step
• 830 to 230 would be 6 hours.

• Now add the 45 remaining minutes

• The total is 6 hours and 45 minutes

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Lets Try This Problem Another Way

• Students depart the buses at 830 a.m. They get
  back on the buses around 315p.m. How long is
  the school day?
• You could also say from 830 330 is 7 hours.
• Then subtract the minutes as you count back from
  330 to 315. This will give you a total of 6
  hours 45 minutes.

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Time Word Problems

• Kim spent the afternoon watching her favorite
  movie. She started the DVD at 234. She was
  interrupted by a phone call from her sister at
  342. She didnt pause the movie. She ended her
  conversation at 428. The movie ended at 516.
  How long did she actually spend watching the
  movie?

Can you think of more than one way to solve this
problem?
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One way to solve the problem

• You could calculate the length of the movie,
  calculate the length of the phone conversation,
  and then find the difference.
• The movie lasted from 234p.m to 516p.m. How
  long was the movie?
• How long did the conversation last? She talked
  from 342 to 428

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ONLINE CLOCK Link

• The movie lasted from 234p.m to 516p.m. How
  long was the movie?
• Start time was 234pm
• 1 hour later it is 334
• 2 hours later it is 434
• From 434 pm to 516 pm 42 min
• The movie lasted 2 hours and 42 minutes

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How much time was spent talking?

• She talked from 342 p.m. to 428p.m Count from
  342pm to 428pm
• in 10-minute increments
• 342 Conversation begins
• 352 10 minutes later
• 402 20 minutes later
• 412 30 minutes later
• 422 40 minutes later NOW add 6 more
• 428 46 minutes later

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• The movie lasted
• 2 hours and 42 minutes
• We need to take away the 46 minutes she spent
  talking
• First take away the 42 minutes and we have 2
  hours left.
• Then take away 4 more minutes
• We now have 1 hour and 56 minutes of time she
  spent actually watching the movie.

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Another way to solve the problem

• You could calculate how long she watched before
  the conversation started and then how long she
  watched after the conversation.
• She watched from 234p.m to 342 p.m.
• HOW MUCH TIME IS THAT?
• She watched from 428p.m to 516 p.m.
• HOW MUCH TIME IS THAT?

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• She watched from 234p.m to 342 p.m.
• HOW MUCH TIME IS THAT?
• From 234 pm to 334pm is ONE HOUR
• From 334 to 342 is another 8 MINUTES
• 1 hour and 8 minutes.
• She also watched from 428p.m to 516 p.m.
• Count from 428pm to 518pm in 10-minute
  increments
• 428 438 448
  458 508 516
• That is 48 minutes
• Add 1 hour and 8 minutes to 48 minutes
• Total is 1 hour and 56 minutes

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1
Elapsed Time Practice

• Jonas left home at 1015 a.m. to head to the
  pool. He arrived at 1037a.m.
• How long was his ride?

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2
Elapsed Time Practice

• At 433 Shelly left the grocery store. She spent
  1 hour and 16 minutes shopping.
• What time did she arrive at the store?

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3
Elapsed Time Practice

• Devin jogged with his dog from 114 p.m. to 303
  p.m. He stopped for a 15 minute break. How long
  did he spend jogging?

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4
Elapsed Time Practice

• Oprah and Gayle left Chicago at 800 a.m. and
  arrived in Cleveland at 1143 a.m.
• They stopped for lunch and were back on the road
  at 115 p.m.
• They arrived in Erie, PA at 916 p.m.
• How much time did they spend driving?
• How long was their lunch break?

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5
Elapsed Time Practice

• The prom decorating committee arrived at the high
  school at 430 to set up. The prom started at
  730p.m. and ended at 100 a.m. The decorating
  committee left when the prom ended.
• How much time did the committee members spend at
  the school on prom night?
• What information in this problem is not needed?

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Let's Check Our Answers
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1
Elapsed Time Practice

• Jonas left home at 1015 a.m. to head to the
  pool. He arrived at 1037a.m.
• How long was his ride?

22 minutes
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2
Elapsed Time Practice

• At 433 p.m. Shelly left the grocery store. She
  spent 1 hour and 16 minutes shopping.
• What time did she arrive at the store?

Arrival Time 317p.m.
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3
Elapsed Time Practice

• Devin jogged with his dog from 114 p.m. to 303
  p.m. He stopped for a 15 minute break. How long
  did he spend jogging?

1 hour 34 minutes
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Elapsed Time Practice
They drove 11 hrs 44 min

• Oprah and Gayle left Chicago at 800 a.m. and
  arrived in Cleveland at 1143 a.m.
• They stopped for lunch and were back on the road
  at 115 p.m.
• They arrived in Erie, PA at 916 p.m.
• How much time did they spend driving?
• How long was their lunch break?

Lunch lasted 1 hr 32 min
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5
Elapsed Time Practice

• How much time did the committee members spend at
  the school on prom night?
• What information in this problem is not needed?

8 hrs 30 min 8.5 hours 8 and a half hours
The prom started at 730p.m.
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More Problems to Solve
MATCHING ELAPSED TIME