INTRODUCTION 1
CHAPTER ONE：THE SCIENTIST AT WORK 1
1．What Is Science？ 1
2．Observation 2
3．Instruments 3
4．Questions 5
5．Experimenting 6
6．Finding Answers 9
7．Stating a Problem 10
8．An Hypothesis 12
9．The Answer 13
10．Summing Up 15
CHAPTER TWO：EXPERIMENTING WITH ELECTRICITY 17
1．What Is Electricity？ 17
2．Using Electricity 18
3．The Dry Cell 19
4．Sockets and Wires 20
5．Lighting a Bulb 22
6．A Complete Circuit and a Switch 24
7．Conductors and Nonconductors 26
8．A Short Circuit 28
9．A Fuse 30
10．Heat and Electricity 32
11．The Electric-Light Bulb 33
12．Wiring the Circuits 35
13．Batteries and Ways to Obtain Electricity 37
14．Adding Volts 38
15．Electricity in Review 40
CHAPTER THREE：USING MACHINES 41
1．A Machine 41
2．The Lever 42
3．Kinds of Levers 44
4．A Lever for Experimenting 46
5．Pulleys 48
6．Wheel and Axle 50
7．The Inclined Plane 53
8．The Screw 55
9．The Wedge 57
10．The Power Shovel 58
11．Elevators 60
CHAPTER FOUR：WORKING WITH CHEMICALS 63
1．Molecules and Atoms ＆ Elements and Com-pounds 63
2．Matter and Change 66
3．Describing Chemical Changes 69
4．“Breaking”a Compound ＆ Making a Com-pound 73
5．Some Important Chemical Changes 76
6．Chemicals Every Day 78
CHAPTER FIVE：INTO SPACE WITH SATELLITES 79
1．Launching Satellites 79
2．Rocket Power 81
3．Satellite Rockets 82
4．Satellites—Up and Down 84
5．Satellite Instruments 86
词汇表 89