A.M. and P.M. Basics (Day & Night Sequences) - First Grade Mathematics

Did you know that every single day has two eight o'clocks, two twelve o'clocks, and two seven o'clocks? That is because a full day has 24 hours, but our standard clocks only have 12 numbers on their faces! To make a full day, the hour hand must travel around the clock circle two complete times: once while the sun is shining, and once while the moon is glowing in the night sky. To tell the two halves of the day apart, mathematicians use two short abbreviations: A.M. and P.M. In this chapter, you will master the difference between A.M. and P.M. and sequence your daily routines.

What Do A.M. and P.M. Mean?

A.M. and P.M. come from Latin words that describe the position of the sun in the sky.

The Two Halves of a 24-Hour Day:

[ A.M. ] -> MORNING (Midnight to Midday / Noon)
            From 12:00 midnight (sleeping) to 11:59 morning (eating lunch).

[ P.M. ] -> AFTERNOON & EVENING (Noon to Midnight)
            From 12:00 noon (sun high in the sky) to 11:59 night (deep sleep).

The Midnight Boundary

A brand-new day officially begins at 12:00 midnight, while you are sound asleep in bed! From that exact moment until noon lunchtime, all times are labeled A.M. At 12:00 noon, lunchtime arrives and the second half of the day begins. From noon until midnight, all times are labeled P.M.

Everyday Routines in A.M. and P.M.

Let us trace a typical first grader's day along the timeline of A.M. and P.M.

A Day in Your Life:

TIME         LABEL    ACTIVITY
7:00         A.M.     Waking up, brushing teeth, eating breakfast.
8:30         A.M.     Arriving at school, greeting friends.
12:00        P.M.     NOON! Eating lunch in the cafeteria.
3:30         P.M.     School finishes; playing outside on the playground.
6:00         P.M.     Eating dinner with family.
8:00         P.M.     Reading a bedtime story, turning off lights.
12:00        A.M.     MIDNIGHT! Sleeping soundly under the stars.

The 7:00 A.M. vs. 7:00 P.M. Test

Look at 7:00: At 7:00 A.M., you are waking up and pouring a bowl of cereal. At 7:00 P.M., the sun is setting and you are finishing dinner or taking a warm bath. The label A.M. or P.M. completely changes what you are doing!

Sequencing Events with Time

Mathematicians use time words to place events in proper chronological order: Before: An event that happened earlier (e.g., you put on socks before you put on shoes). After: An event that happens later (e.g., dessert comes after dinner). Between: An event that happens in the middle of two other events.

Practice Exercises

Exercise 1: What do the letters A.M. and P.M. represent, and what major event marks the switch from A.M. to P.M.?

Exercise 2: Decide whether each activity happens in the A.M. or the P.M.: Eating breakfast before school: _ Looking at the moon and stars before bed: Waking up to the morning alarm: _ Playing soccer after school at 4:00:

Exercise 3: Why does an analog clock only have 12 numbers if a whole day has 24 hours?

Exercise 4: Put these three daily events in chronological order from earliest to latest: Eating dinner (6:00 P.M.), Waking up (7:00 A.M.), Eating lunch (12:00 P.M.).

Solutions and Explanations

Solution to Exercise 1: A.M. represents morning hours (from midnight to noon), and P.M. represents afternoon and evening hours (from noon to midnight). The switch from A.M. to P.M. occurs at 12:00 noon (midday).

Solution to Exercise 2: Eating breakfast: A.M. Looking at the stars before bed: P.M. Waking up to the morning alarm: A.M. Playing soccer after school at 4:00: P.M.

Solution to Exercise 3: An analog clock has 12 numbers because it is designed to measure half of a day on each revolution. The hour hand makes two complete 12-hour laps around the clock face every 24 hours (one lap for A.M. and one lap for P.M.).

Solution to Exercise 4: In order from earliest to latest:
1. Waking up (7:00 A.M.)

2. Eating lunch (12:00 P.M.)

3. Eating dinner (6:00 P.M.)