or with the light shining right in your face instead of coming over
your shoulder. But sometimes it is caused by the fact that your eyes
are not just the right shape; and then the only way to relieve it is
to have proper glasses, or spectacles, fitted, which will make up for
this too flat or too round shape, or too large or too small size, of
your eyes.

If you cannot see clearly what is written on the blackboard when the
light falls upon it from behind you, or above; or if, in a good light,
you cannot read the words in your book quite easily, without straining
at all, when you hold the book either at arm's length or a foot from
your face; or if your head aches or your eyes begin to feel tired or
uncomfortable, or the letters begin to blur, after you have read
steadily--say, for half an hour,--it is a pretty sure sign that there
is some trouble with your eyes. Then you had better have them examined
at once by your family doctor or by the school doctor. In many schools
now there are doctors to test the children's eyes, and ears, too, so
that each child may have a chance to see and hear everything that the
other children can see and hear.

Not very many years ago people thought that glasses were only for old
people, but now we know that many children's eyes need glasses, too. I
knew a little girl whose sight was so poor that when she was standing
and looked down at the grass, she couldn't see the green blades. She
thought that the grass looked like a green blur to everyone, just as
it did to her; and so she never said anything about it. She was twelve
or thirteen years old before she found out that she couldn't see
clearly. Of course, trying hard to see things gave her a headache and
made her tired and cross. So some one took her to a doctor, and he saw
at once what was the matter and fitted her with glasses. Soon she was