How may stains be removed from the teeth? What substances injure the teeth? What about cracking nuts and other hard substances with the teeth? How many teeth has a child? A man? When do the second teeth begin to appear? How long is it intended they should last? What sometimes takes place? What should be done? What will follow if this advice is not heeded? How are loose teeth generally pulled? Have you ever known of a boy or girl pulling his or her own teeth? What must you watch for and do? Is there any need of such care? What is said of some children? When should you go to the dentist? [Illustration: MUSCLES.] CHAPTER VII. EXERCISE. Boys and girls are not likely to believe they need any instruction as to exercise. They are so fond of play that all they ask is a chance and they will use it to the utmost. That form of exercise is best which brings most muscles into action. It should not be too violent nor continued after one is tired. It should be in the open air, and some kind of game is preferable because it also engages and interests the mind. TESTS OF SKILL. Base-ball, rowing, foot-ball, hare and hounds, skating, lacrosse, lawn tennis and similar tests of skill have become so popular in this country that the young need to be restrained from indulging too much in them. After one's school-days are over and a young man takes up some sedentary occupation, he should manage to gain exercise every day. The gymnasiums afford the best forms of exercise, but boys and girls can walk, run, and use some of the simpler forms of gymnastics at their homes. They should make sure they breathe pure air, that they do not form bad habits, and are regular in everything daily required of them. * * * * * What form of exercise is best? What should be guarded against? Where should it be? What is preferable? What games are popular? What should every boy do, after his school-days are over? What of the gymnasiums? What can be done by all boys and girls? Of what should they make sure? CHAPTER VIII. THE ART OF SWIMMING. Every boy and girl should learn to swim. Instances are likely to arise, where a knowledge of the art will not only enable you to save your own life, but that of some dear friend. [Illustration] When ready to take your first lesson in swimming, plunge into the water until the head and body are cooled. Then, standing where the water reaches your waist, lie down gently on your face, head erect as if walking, with the mouth just above the surface. Lift your feet from the bottom and strike them out in imitation of a frog. At the same instant or a second later, throw your arms, palms outward, from the front of your breast, drawing them in and striking out as before.