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

2. Vocabulary
Digital clock: instrument that reads time in a numerical format
Analog clock: time represented by hands on a dial

3. Digital Clocks When reading a digital clock, 5 hours and 8 minutes
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

4. 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

5. Counting by 5s 60 5 55 10 50 45 15 40 20 25 35 30

6. 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

7. Elapsed Time Elapsed time – time that has passed
Ex: If I say that the party lasted from 5:30 PM
to 7:30 PM, then 2 hours passed, or
elapsed.
It can be measured in:
seconds
minutes
hours
days
weeks
Picturing or using
a clock
will help

8. 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 8:30 PM
and ended at 9:00 PM. How many minutes did the program last?

9. Types of Elapsed Time Problems
Ex: The TV program started at 6:30 PM & ended at 7:00 PM. How many minutes did the program last?
To calculate the total minutes
Picture a clock showing 6:30
Count by 5s until you reach 7:00

10. Types of Elapsed Time Problems
Ex: The TV program started at 6:30 PM & ended at 7:00 PM. How many minutes did the program last?
To calculate the total minutes
Picture a clock showing 6:30
Count by 5s until you reach 7:00
Before revealing “Notice that the clock…” ask students to read what time does the clock say.
* Notice that the clock now shows 7:00

11. Types of Elapsed Time Problems
Ex: The TV program started at 6:30 PM & ended at 7:00 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

12. 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 1:30 PM
and lasted for 30 minutes. When did the program end?

13. Types of Elapsed Time Problems
Ex: The TV program started at 1:30 PM
and lasted for 30 minutes. When did the program end?
To calculate the program end time
You’re 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)

14. Types of Elapsed Time Problems
Ex: The TV program started at 1:30 PM and
lasted for 30 minutes. When did the program end?
To calculate the program end time
When working with units of measurement, it’s
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: 2:00 PM

15. Types of Elapsed Time Problems
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 2:00. When did the program
start?

16. Types of Elapsed Time Problems
Ex: The TV program lasted for 30 minutes
and ended at 2:00 PM. When did the
program start?
To calculate the start time
There are 2 hours to work with since the
program ended at 2:00.
60 minutes equal 1 hour, so subtract 30
minutes from 60 minutes (60 min – 30 min =
30 min)
The time that’s left is 1 hour and 30 minutes
Answer: 1:30 PM

17. Let’s practice some elapsed time problem!!
mathFROG - Fun Resources & Online Games

18. Elapsed Time Practice 15 minutes
How much time has gone by between the times on the first and second clocks?
15 minutes
15 minutes

19. Elapsed Time Practice
How much time has gone by between the times on the first and second clocks?
55 minutes
55 minutes

20. 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

21. 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

22. Questions???