xiv TABLE OF CONTENTS 



UNIT VIII. GETTING ACQUAINTED WITH THE 



STARS 187 



PROBLEM 



I. How FAR AWAY ARE THE STARS? 189 



II. WHY Do THE STARS APPEAR TO MOVE? .... 196 



III. How TO GET ACQUAINTED WITH THE CONSTELLATIONS . 200 



UNIT IX. ROCKS AND SOIL . . . 213 



I. How WERE THE ROCKS FORMED? 216 



II. WHAT Is THE STORY OF THE FOSSILS? . . ... 220 



III. How Is SOIL MADE? 228 



IV. WHAT SOILS ARE BEST FOR AGRICULTURE? .... 236 



UNIT X. LIVING THINGS IN THEIR ENVIRONMENT . 249 



I. WHAT Is BEING ALIVE? 252 



II. How Do GREEN PLANTS SOLVE THEIR LIFE PROBLEMS? . 257 



III. How Do ANIMALS PERFORM THE BUSINESS OF LIFE? . 266 



IV. WHAT LIVING THINGS ARE FOUND IN MY YARD OR GARDEN ? 270 



V. LIFE IN STREAM AND POND 281 



VI. LIFE IN FOREST AND ON THE MOUNTAINS .... 288 



VII. LIFE ON THE SEASHORE 294 



UNIT XL THE FOODS WE EAT . . 307 



I. WHAT ARE FOODS AND WHERE Do THEY COME FROM? . 309 



II. How Do WE USE FOODS? 313 



III. SHOULD EVERYBODY EAT THE SAME KINDS AND AMOUNTS OF 



FOOD? 326 



IV. WHY Do FOODS SPOIL? 333 



V. How MAY WE KEEP FOODS FROM SPOILING? . . . 339 



UNIT XII. THE HUMAN MACHINE AND HOW TO 



CARE FOR IT 351 



I. How DOES THE HUMAN MACHINE OIFFER FROM AN AUTO- 



MOBILE? 354 



II. How Is THE HUMAN MACHINE PROTECTED? . . 359 



III. How DOES THE BODY MOVE? 368 



IV. How DOES THE HUMAN MACHINE MAKE USE OF FOOD? . 375 



V. How Do WE CONTROL THE HUMAN MACHINE? . . . 384 



VI. ALCOHOL, NARCOTICS, AND THE HUMAN MACHINE . . 392 



VII. WHAT Is THE IMPORTANCE OF SAFETY EDUCATION AND FIRST 



AID? 399 



GLOSSARY 417 



INDEX 425 



