The girl wants just as much lung capacity as she can possibly get.  We find that the girl during those years is a little taller and a little heavier than the boy, and she needs more oxygen to every pound of waste in the body than the boy does, because the waste is going on faster.  The average girl has about three-fourths as much lung capacity for every pound of the waste in the body, as has the average boy.  What the girl needs is more lung capacity to get in more oxygen.  How is she going to get the lung capacity sitting in the house?  How is she going to get it when she is tied down in the grammar school room with a book before her eyes?

The worst of it all is that the girl leaves off playing games in the open air just about the time when she needs them the most, and not having the open air play and the open air games, she can’t get the lung capacity and the oxygen.  Another thing that hinders the girl is this:  there is no place for her to play where she can do all she wants to and not have people looking over the fence and finding fault with her for having a good time.  Every girl ought to have a place where she can play in the open air and not be bothered and we ought to get more and more games for girls of that age.  Another thing, the exercise should not be too severe.  Don’t kill a girl with physical training; because you can kill her that way just as you can kill her with books.  Some of our physical training is too severe for a girl of that age.  She must have plenty of the right kinds of games and they should be in the open air, and they should be such as she will enjoy and love; if they are not of that kind it won’t help a great deal.  If you can build up lung capacity in that way then you are drawing in the oxygen; then you are getting out the waste, and you will find the girl will come out all right in nine cases out of ten.

It is a fact, proved by physical examination, that all during this period the better scholars have the larger lung capacity.  Those of you who have taught in the grammar schools year after year will know that a bright girl, one that has been very bright, will have a year when she will come to you and will be absolutely stupid and can’t learn.  “What ails the girl?” you wonder.  She will tell you, “I don’t know what ails me; I can’t learn anything.  I have become a fool and I was not always one.”  The trouble is with the lung capacity; it isn’t with the brain; the brain is all right.  If you tell that girl to wake up in order to make up that lack of mental ability by studying harder, you are doing the unpardonable sin.  I am telling it to you straight.  That is not the remedy.  The remedy is more play in the open air, then you will find that that girl’s brain will clear up.  Many a poor girl has been put in poor condition by being urged to study hard, when the fault was that nobody knew enough to turn her out into the fresh air which the Lord intended she should have.