Our minds grow as our bodies do, by healthful exercise--little at a time, with plenty of rest and change of occupation between the periods of work. That is why our school studies are arranged as they are: instead of one subject being studied all the morning, or all day, four or five subjects are studied for twenty or thirty minutes each, and a change is made to another before our minds become over-tired and begin poisoning themselves with fatigue toxins. A subject that is rather hard for us is followed by one that is easier; and the hardest subjects in the course are usually taken up early in the morning session, or after recess, or early in the afternoon, when we are well-rested and feeling fresh and ready for work. We should try to keep our bodies and our brains and our sight and hearing in the very best possible condition for our work, so as to come up to each task that we have to master keen and fresh and clear-headed, rather than to take pride in spending so many hours a day studying in a half-tired, half-hearted, listless kind of way. You will find that you will be able to master a lesson and see through a problem in half the time if you get plenty of sleep in a room with the windows open, play a great deal out-of-doors, and do not hurry through your meals for either school or play. [Illustration: AN OBSTACLE RACE] Study just as you play ball when you are trying to make a place on the team. Bend every energy that you have to that one thing, and forget everything else, until you have finished it. You can do more work in fifteen minutes in this way than you can in forty minutes of sitting and looking out of the window and wondering how much longer the study period is to last, and what the next chapter is about in the story that you are reading at home, or what you are going to wear to the party next week.