1．Dog Helps Crippled Boy 1
2．Hermit Crabs Learn What Not to Eat 3
3．Bacteria 6
4．Why Do Birds Sing? 9
5．Tornado Lifts Woman and Dog 12
6．Electricity Stops Bleeding in Humans 15
7．People Who Are Cold May Need Iron 18
8．Vitamins 21
9．What You Can Do To Save Energy 25
10．The Compass 28
11．Geothermal Energy 32
12．Microwave Ovens 36
13．Students Name New Space Shuttle 39
14．Student Invention Helps Astronauts 42
15．Cosmonaut Grows Taller in Space 45
16．Air Pollution 49
17．World Hunger 53
18．Midafternoon Naps Are Normal 57
19．Doctors Grow Brain Cells in Lab 60
20．Dolphin and Seal 63
21．How Cats Survive From High Falls 66
22．Spring Peepers 71
23．I Took a Trip into Space 75
24．Biosphere Ⅱ 78
25．Pilot Nearly Sucked out of Plane 83
26．Solar Energy 88
27．Underground Temperatures 91
28．Sonar 95
29．Scientists Make Diamonds From Sewer Gas 98
30．Friction 101
31．Smart Home Does Everything 104
32．Future Devices Will Make Life Easier 109
33．Scientists Help Save Pandas 114
34．Water Pollution 118
Key to Exercises 123