TABLE OF CONTENTS 



PAGE 



UNIT I. GETTING ACQUAINTED WITH THINGS. 1 



PROBLEM 



I. How Do WE GET ACQUAINTED WITH THINGS? ... 3 



II. WHAT Is OUR ENVIRONMENT AND How Do WE USE IT? . 11 



UNIT II. LIFE DEPENDS ON ADAPTATIONS . 25 



I. WHAT ARE ADAPTATIONS AND WHAT Do THEY Do? . . 26 



II. How ARE WE FITTED TO LIVE IN OUR ENVIRONMENT? . 33 



UNIT III. LIVING IN AN OCEAN OF AIR . 43 



I. WHAT MAKES THE AIR USEFUL TO MAN? .... 45 



II. OF WHAT IMPORTANCE Is ATMOSPHERIC PRESSURE? . . 52 



III. How Do WE USE AIR? 59 



IV. How Do WE BREATHE? 67 



UNIT IV. WATER AND ITS EVERY-DAY USES . 79 



I. WHAT Is WATER? .82 



II. WHAT USES Do WE MAKE OF WATER? .... 88 



UNIT V. HOW WE USE HEAT . . .103 



I. How Is HEAT PRODUCED? . . . . . . . 105 



II. WHAT ARE SOME OF THE CHARACTERISTICS OF HEAT? . 109 



III. How DOES CLOTHING AFFECT THE HEAT OF THE BODY? . 117 



UNIT VI. HOW WE USE LIGHT . . 127 



I. How Do I USE LIGHT? 129 



II. WHAT ARE SOME OF THE PROPERTIES OF LIGHT? . . 134 



III. How ARE PHOTOGRAPHS MADE? 142 



IV. How DOES THE EYE RESEMBLE THE CAMERA? . . . 149 



V. WHAT Is COLOR? .154 



UNIT VII. HOW WE MAY PRODUCE ELECTRICITY 



AND MAGNETISM .... 165 



I. WHAT CAN MAGNETS Do? 167 



II. WHAT ARE SOME WAYS OF PRODUCING ELECTRICITY? . 173 



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