Lesson 1 1
Text:How Nature Breaks Rocks 1
Reading Materials 9
Ⅰ．Weight On and Off the Earth 9
Ⅱ．Falling Bodies and Their Weight 14
Lesson 2 17
Text:Star Wars-and Einstein 17
Reading Materials 25
Ⅰ．Atomic Clocks 25
Ⅱ．Physical and Chemical Changes 28
Lesson 3 31
Text:Christopher Columbus 31
Reading Materials 39
Ⅰ．Columbus and America 39
Ⅱ．The Travels ofMarco Polo 42
Lesson 4 46
Text:Plants 46
Reading Materials 53
Ⅰ．Save the World 53
Ⅱ．Early Plant Life-the Algae 55
Lesson 5 58
Text:Spare Parts for Human Body 58
Reading Materials 66
Ⅰ．What Is Cancer? 66
Ⅱ．Permeability 69
Lesson 6 72
Text:Temperatures and Thermometers 72
Reading Materials 81
Ⅰ．What Is Heat? 81
Ⅱ．Can We'Make'Energy? 84
Lesson 7 86
Text:Animals in Danger 86
Reading Materials 93
Ⅰ．Why Does a Male Bird Have Brightercolors than the Female? 93
Ⅱ．Food Chains 96
Lesson 8 98
Text:Dealing with Radiation Dangers 98
Reading Materials 105
Ⅰ．Matter and Energy 105
Ⅱ．Radiant Energy 109
Lesson 9 112
Text:Through the Earth's Crust 112
Reading Materials 120
Ⅰ．The Interior of the Earth 120
Ⅱ．Mineral Oil 124
Lesson 10 128
Text:Refrigeration and Refrigerators 128
Reading Materials 135
Ⅰ．How Does a Refrigerator Produce Cold? 135
Ⅱ．Protection of Food Against Bacterial Action 138
Lesson 11 141
Text:A Warmer or A Colder Earth? 141
Reading Materials 148
Ⅰ．Climate and Vegetation 148
Ⅱ．What People Don't Know about Air 151
Lesson 12 155
Text:The Value of Transistors 155
Reading Materials 163
Ⅰ．Microelectronics 163
Ⅱ．Transistor 166
Lesson 13 170
Text:Alfred Nobel-A Man of Contrasts 170
Reading Materials 178
Ⅰ．How Scientists Work 178
Ⅱ．Abilities 182
Lesson 14 187
Text:Metals and Ores 187
Reading Materials 196
Ⅰ．How We Use Metals 196
Ⅱ．Hot Metal 200
Lesson 15 203
Text:The Story of Eyes 203
Reading Materials 211
Ⅰ．Can Animals See in Color? 211
Ⅱ．Bees and Colour 214
Vocabulary 217