Telling and Writing Time to the Hour (o'clock) - First Grade Mathematics

Every hour of the day begins with a special celebration: the minute hand reaches the very peak of the clock face, pointing straight up at 12! Whenever the long minute hand points straight up to 12, we say that it is "o'clock." The phrase "o'clock" is a wonderful old-fashioned contraction that means "of the clock." In this chapter, you will master reading time to the hour on analog and digital clocks, learn how to write the time with numbers and words, and draw clock hands in the correct positions.

The Rule of O'Clock

Whenever an exact hour begins, the two clock hands follow a strict, unchanging rule:

The O'Clock Rule:
1. The LONG minute hand points straight up at the 12!
2. The SHORT hour hand points directly at the hour number!

Clock Showing 4:00 (Four O'Clock):
                 12  <--- Long Hand points straight up!
            11    |   1
        10        |       2
       9          +         3
        8          \      4  <--- Short Hand points to 4!
             7        5
                 6

Reading the Hour

Because the long hand is standing at attention at 12, the minutes count is zero. To read the time, simply look at the short hour hand! If the short hand points to 1, it is 1:00 (one o'clock). If it points to 4, it is 4:00 (four o'clock). If it points to 9, it is 9:00 (nine o'clock).

Writing Time to the Hour

Mathematicians write time to the hour in two different ways: with words and with numbers.

Writing Formats for Time to the Hour:
Word Format:           Digital Number Format:
One o'clock                 1:00
Two o'clock                 2:00
Three o'clock               3:00
Four o'clock                4:00
Five o'clock                5:00
Six o'clock                 6:00
Seven o'clock               7:00
Eight o'clock               8:00
Nine o'clock                9:00
Ten o'clock                10:00
Eleven o'clock             11:00
Twelve o'clock             12:00

Notice the Two Zeros (:00)

In digital time, the two zeros after the colon mean zero minutes have passed in the new hour. It is a brand-new hour!

Drawing Clock Hands Accurately

When you draw hands on a blank clock face, follow these guidelines: Step 1: Draw the long minute hand first: make it tall and thin, extending almost all the way to touch the 12 at the top. Step 2: Draw the short hour hand next: make it noticeably shorter (about halfway across the circle) and point it straight at the hour number.

Comparing Hand Lengths in a Drawing:
Center to 12 (Minute Hand):  +-------------------> (LONG!)
Center to 4 (Hour Hand):    +========>            (SHORT!)

Practice Exercises

Exercise 1: An analog clock has its minute hand pointing to 12 and its hour hand pointing to 8. What time is it? Write the time using words and using digital numerals.

Exercise 2: Write the digital time for each of these word phrases: Two o'clock = : Seven o'clock = : Eleven o'clock = :

Exercise 3: Where does the long minute hand always point when the time is an exact "o'clock" hour?

Exercise 4: Draw or describe how you would set an analog clock to show 12:00. Where do the two hands point?

Solutions and Explanations

Solution to Exercise 1: The time is eight o'clock. In digital numerals, it is written as 8:00.

Solution to Exercise 2: Two o'clock = 2:00 Seven o'clock = 7:00 Eleven o'clock = 11:00

Solution to Exercise 3: The long minute hand always points straight up to the number 12 at the top of the clock face.

Solution to Exercise 4: At 12:00, both the short hour hand and the long minute hand point straight up at the number 12 together, overlapping each other.