1 A The History of Space Travel 1
1 B Neil Armstrong:First Person on the Moon 3
2 A What Is a Botanist? 5
2 B Do Plants Feel Pain? 7
3 A Lakes and Rivers 9
3 B Cleaning Up Rivers 11
4 A How Flight Is Possible 13
4 B Helicopters:Form and Function 15
5 A Earth's Layers 17
5 B Making a Model of Earth's Layers 19
6 A The Nobel Prizes 21
6 B Doctors Without Borders 23
7 A The Organs of the Body 25
7 B The Importance of Water in the Body 27
8 A Technology for People with Hearing or Visual Impairments 29
8 B Learning Sign Language 31
9 A The Importance of Vitamins and Minerals 33
9 B The Truth About Vitamin C 35
10 A Gymnastics:A Sport of Balance 37
10 B Training to Be a Gymnast 39
11 A Growing Plants from Seeds—Guaranteed! 41
11 B How Seeds Travel 43
12 A Precipitation 45
12 B Classroom Dew-Point Experiment 47
13 A Why Is the Ocean Blue? 49
13 B Primary Colors of Paint and Light 51
14 A How Humans Hear 53
14 B Sound-Wave Interference 55
15 A The History of Numbers 57
15 B Using Geometry to Solve Everyday Problems 59
16 A Venus:Earth's Sister Planet 61
16 B Galileo's Telescope 63
17 A What Is a Reptile? 65
17 B Poisonous Snakes of the United States 67
18 A The Parts of a Flowering Plant 69
18 B Animal Helpers in the Garden 71
19 A Gravity and Air Resistance 73
19 B Streamlined Trains 75
20 A Some Spiders of North America 77
20 B Dr.Charles Turner,Zoologist 79
21 A Plants and Animals in Ponds 81
21 B What Is an Ecosystem? 83
22 A Computer Memory and Storage 85
22 B From Punch Cards to DVDs 87
23 A Signs of Spring 89
23 B Joseph's Nature Journal 91
24 A Stone,Brick,and Concrete 93
24 B Building the Brooklyn Bridge 95
25 A The Tropical Rainforest Biome 97
25 B Saving the Rain Forest 99
附录 101
Answer Key 101
Reading Rate 103
Comprehension Score 104
Comprehension Skills Profile 105