How_To_Be_Good_At_Math

192

Types of 3D shape

Not all clocks look like

the one above. Some

clocks don’t have

hands at all. Others

show all 24 hours in

the day, instead of just

using the numbers

1 to 12.

Telling the time

We measure the passage of time to organise our

everyday lives. Sometimes we need to know how long

something takes, or we need to be in a certain place at

a particular time. We use seconds, minutes, hours, days,

weeks, months, and years to measure time.

MEASUREMENT • TELLING THE TIME MEASUREMENT • TELLING THE TIME

Look at this clock. The numbers around

the edge help us measure which hour

of the day it is. There are 24 hours in a day

• 12 in the morning and 12 in the evening.

The shortest hand on the clock

is the hour hand. It points to which

hour of the day it is.

The marks around the edge of the

clock tell us the minutes of an hour.

There are 60 minutes in one hour.

There are no numbers to tell us precisely

which minute it is. Instead, we use the hour

numbers to help us count up in fives to work it out.

The longer hand points to the minutes.

If we’re writing the time using

the 12-hour clock, we write

a.m. or p.m. to show whether

it’s morning or afternoon.

Some clocks use Roman

numerals to mark the hours.

We looked at Roman numerals

on pages 10-11.

There are 60 seconds in a minute.

Some clocks have a long, thin second

hand that moves quickly around the clock

face – one full turn takes one minute.

24-hour clocks have extra

numbers to count up from

12 to 24, because there are

24 hours in a day.

Digital clocks have no

hands. They tell us the

time with digits. They often

use the 24-hour clock.

Clocks The hands

rotate in this

direction, called

clockwise

Hours Minutes

15 27:

Sometimes the

number 4 is

written “IIII”

192-193_Telling_the_time.indd 192 11/03/2016 16:24