ght in; and this, in any modern and
properly built schoolhouse, is usually arranged for. The fresh air is
drawn in through an opening in the basement and is either heated, so
that it rises, or is blown by fans all over the building. This sort of
fresh air, however, is never quite so good as that which comes
directly from outdoors; so it is generally best to keep at least two
or three windows in each room opened at the top as well, and never to
depend entirely upon the air that comes through the heating system.

Sometimes this may mean a little draft, or current of uncomfortably
cool air, for one or two of you who sit nearest the windows; but your
teacher will always allow you to change your seat if this proves very
unpleasant. If you have plenty of warmth in the room you sit in,
unless the air outside is very cold, this "breeze" won't do you any
harm at all; on the contrary, it will be good for you. Instead of
catching cold from a draft like this, it is from foul, stuffy,
poisonous air, loaded with other people's breaths and the germs
contained in them, that you catch cold.

[Illustration: GARDENS TAKE US OUT OF DOORS]

In fact, staying indoors is usually the reason why people are sick.
They don't go out into the clean fresh air for fear they'll be too
cold! It seems a pity we can't just live out of doors all the time.
Perhaps we shall some day; for doctors are finding out that fresh
outdoor air and good food are the very best medicines known, and the
only "Sure Cures." They are pleasant to take, too. Many cities are
providing outdoor schools for children who have weak lungs or are not
strong in other ways. Perhaps some day all school children will be
allowed to study in the open air at least part of every school day.

II. HEARING AND LISTENING

Now you are all ready to go to work. What are you going to work with?
Books? pencils? paper? Yes, but you have something better than those
and all ready for use. It is that little kit of tools that are
sometimes called our "Five Senses." You remember that we have already
talked about one of them, the sense of touch in the skin. Now which
one are you going to use first this morning? If your teacher talks to
you, I hope it will be the one we call the sense of hearing. Suppose
we try to find out something about this sense of hearing, and begin
with a little experiment.

Take a piece of cork in your hand and lift it up high and then let it
drop into a large basin or tub