Clocks

Time

is

also

measured

in

smaller

units

called

hours,

minutes

and

seconds.

People

use

clocks

to

measure

these

units.

Long

ago,

people

used

shadow

sticks

to

keep

track

of

time.

They

placed

a

stick

straight

up

in

the

ground.

As

the

sun

moved

across

the

sky,

the

stick’s

shadow

moved

in

an

arc

around

the

stick.

People

looked

at

the

shadow

during

daylight

and

knew

the

approximate

time

of

day.

The

sundial

uses

shadows

to

tell

the

time.

A

sundial

has

a

circular

dial

with

the

hours

marked

on

it

and

a

triangular

pointer

in

the

middle.

People

told

time

by

seeing

where

the

pointer’s

shadow

fell

on

the

hour

marks.