Concept 2 of 7
AM, PM & the Calendar
Today's big idea
One day is two 12-hour halves: AM from midnight to noon, PM from noon to midnight.
Same clock face, twice a day, so AM or PM is what tells the two apart.
How it works
👀 What's going on?
Your maths lesson and your bedtime can both be at 8 o'clock. The clock face looks exactly the same for both. Something else has to tell them apart.
💡 Here's the trick
Look at the circle above. It is one whole day of 24 hours, cut into two halves of 12. The AM half runs from 12 midnight round to 12 noon. The PM half runs from 12 noon back to 12 midnight. So midnight is 12 AM and noon is 12 PM.
🪄 How to do it
- 1.Find your time on the circle above and see which half it falls in.
- 2.Write AM for the midnight to noon half, and PM for the noon to midnight half.
- 3.For a date question, use 7 days in a week, 14 in a fortnight, 12 months in a year.
✍️ Try it
A cricket match starts at 7 in the evening. Is that 7 AM or 7 PM? Now a harder one. Your train leaves at 12 noon. Should the ticket say 12 AM or 12 PM?
Evening comes after noon, so the match starts at 7 PM. Noon is where the AM half ends and the PM half begins, so 12 noon is 12 PM. Midnight is the other one, and that is 12 AM.
⚠️ Watch out
You might be thinking 12 AM is the middle of the day, because 12 sits at the top of a clock. It is the opposite. 12 AM is midnight, when you are fast asleep, and 12 PM is lunchtime.
🌟 Why this matters
Alarms, bus timetables and cinema tickets all run on AM and PM. Set an alarm for 6 PM instead of 6 AM and you sleep straight through school. Knowing that a week is 7 days and a fortnight is 14 lets you plan a holiday without a calendar in your hand.
Exam tip: When a time is given with no AM or PM, read the story around it for a morning or evening clue.
Watch me solve one
Quanta solves it
“Watch how I think through one of these — then you try.”
THE PROBLEM
“A train leaves at 11 PM and travels for 3 hours. What time does it arrive, and is that AM or PM?”
- 1
Start at the given time
Departure is 11 PM — late at night. 🌙
- 2
Cross midnight
11 PM + 1 hour = 12 midnight, where PM turns into AM.
- 3
Add the last 2 hours
12 AM + 2 hours = 2 AM.
- 4
Answer ✓
It arrives at 2 AM
Now you try one — same steps, different story 👇
See it in action
⚡ Time to play!
Is this an AM (morning) or PM (evening) event?
AM / PM · ROUND 1 OF 4
☀️
Sunrise jog
6:00
Quick check
✅ VERIFICATION
Which of these happens in the AM half of the day?
⚡ Finish the activity above first to answer.
Keep going!
Up next: Calendar Day-Arithmetic
Divide by 7, keep the remainder, count that many forward.