Time and Duration
Time can be read in 12-hour and 24-hour formats. Duration is how long something lasts, calculated by finding the difference between start and end times.
What You Need to Know
Key Concept Diagram
12-hour time uses am (before noon) and pm (afternoon/evening)
24-hour time runs from 0000 (midnight) to 2359, avoiding am/pm
Duration = end time − start time
To find elapsed time, count the hours and minutes between two times
Key Vocabulary
Duration
The length of time an event lasts
am
The period from midnight to noon (ante meridiem)
pm
The period from noon to midnight (post meridiem)
24-hour time
A time format using numbers from 0000 to 2359 with no am/pm
Knowledge Check
Select the correct answer for each question. Click "Check Answer" to see if you are right.
Question 1
A movie starts at 2:15 pm and finishes at 4:45 pm. How long is it?
Question 2
What is 3:30 pm in 24-hour time?
Question 3
School starts at 0845 and finishes at 1520. How long is the school day?
Key Concepts Summary
- ●12-hour time uses am (before noon) and pm (afternoon/evening)
- ●24-hour time runs from 0000 (midnight) to 2359, avoiding am/pm
- ●Duration = end time − start time
- ●To find elapsed time, count the hours and minutes between two times