Digital/ Analog Time

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Digital/ Analog Time

• 4th Strategies for Your Toolbox in Solving
  Problems Involving Digital/ Analog Time

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Vocabulary

• Digital clock instrument that reads time in a
  numerical format
• Analog clock time represented by hands on a dial

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Digital Clocks

• When reading a digital clock,
• the 1st number to the left of the colon is the
  hour
• the 2nd number to the right of the colon is the
  minutes

2nd number
1st number
5 hours and 8 minutes
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Analog Clocks

• Reading an analog clock
• short hand represents the hour
• long hand represents minutes
• hour short word short hand
• minutes long word long hand
• count by 5s to find total minutes if minute hand
  is on a number 1-12, otherwise count by 1s

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Counting by 5s
60
5
55
10
50
15
45
20
40
25
35
30
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Toolbox Strategies for Reading/ Matching Digital
Analog Time

• 1st number on a digital clock always matches
  number the short hand is on
• if the short hand is between 2 numbers, the hour
  is the lesser of the 2 numbers
• Count Us In Games - Game 10
• Aplusmath.com Flashcards Analog Clocks

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Elapsed Time

• Elapsed time time that has passed

Ex If I say that the party lasted from 530 PM
to 730 PM, then 2 hours passed, or
elapsed.

• It can be measured in
• seconds
• minutes
• hours
• days
• weeks

Picturing or using a clock will help
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Types of Elapsed Time Problems

• 1. You know when an event started and when it
  ended. You have to find the amount of time that
  has passed.

Ex The TV program started at 830 PM and ended
at 900 PM. How many minutes did the program
last?
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Types of Elapsed Time Problems
Ex The TV program started at 630 PM ended at
700 PM. How many minutes did the program last?

• To calculate the total minutes
• Picture a clock showing 630
• Count by 5s until you reach 700

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Types of Elapsed Time Problems
Ex The TV program started at 630 PM ended at
700 PM. How many minutes did the program last?
To calculate the total minutes

• Picture a clock showing 630
• Count by 5s until you reach 700

Notice that the clock now shows 700
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Types of Elapsed Time Problems
Ex The TV program started at 630 PM ended at
700 PM. How many minutes did the program last?

• To calculate the total minutes (strategy 2)
• Since the question asks about minutes, subtract
  them (30 min 00 min 30 min)

- Answer 30 minutes
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Types of Elapsed Time Problems

• 2. You know when an event started and how long it
  will last. You have to find when the event will
  end.

Ex The TV program started at 130 PM and
lasted for 30 minutes. When did the program end?
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Types of Elapsed Time Problems

• Ex The TV program started at 130 PM
• and lasted for 30 minutes. When did the program
  end?

• To calculate the program end time
• Youre told how long the program
• lasted in minutes. Add the minutes from the
• start time to the minutes of how long the
• program lasted. (30 min 30 min 60 min)

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Types of Elapsed Time Problems

• Ex The TV program started at 130 PM and
• lasted for 30 minutes. When did the program end?

• To calculate the program end time
• When working with units of measurement, its
• best to use easy numbers so whenever possible
• convert to a unit that reduces a bigger number.

• 60 minutes is equal to 1 hour so add the hours
  
• 1hour from the start time to 1 hour from the
• minutes added together (1 hr 1 hr 2 hrs)

• Answer 200 PM

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Types of Elapsed Time Problems

1. You know when the even will end, and how long it
   will last so you have to find when the event will
   begin.

• Ex The TV program lasted for 30 minutes
• and ended at 200. When did the program
• start?

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Types of Elapsed Time Problems

• Ex The TV program lasted for 30 minutes
• and ended at 200 PM. When did the
• program start?

• To calculate the start time
• There are 2 hours to work with since the
• program ended at 200.

• 60 minutes equal 1 hour, so subtract 30
• minutes from 60 minutes (60 min 30 min
• 30 min)

• The time thats left is 1 hour and 30 minutes

• Answer 130 PM

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Elapsed Time
Lets practice some elapsed time problem!!
mathFROG - Fun Resources Online Games
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Elapsed Time Practice
How much time has gone by between the times on
the first and second clocks?
15 minutes
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Elapsed Time Practice
How much time has gone by between the times on
the first and second clocks?
55 minutes
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Elapsed Time Practice
Maureen started her homework at 7.20 p.m. She
finished it at 8.05 p.m. How long did she take to
do her homework?
50 minutes
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Toolbox Checklist for Solving Elapsed Time
Problems

• Analog clock (You can make, draw, or use
• one that your teacher may provide.)

• Knowledge to remember hour hand short
• word short hand minute hand long word
• long hand

• Manipulate the hands to show times

• Knowledge to remember 60 seconds 1
• minute 60 minutes 1 hour

• Count by 5s

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Questions???