What Are You Wondering About? xii --
How does Earth maintain its speed of rotation? Why doesn't it slow down? 2 --
How was Earth formed, and what was it like in the beginning? 5 --
Does air weigh anything? 8 --
Why do trees and other plants take in carbon dioxide, while we take in oxygen? 10 --
What makes a volcano erupt? 13 --
Why don't we have ice ages anymore? 17 --
If you dug all the way through Earth, would you end up in space? 20 --
What causes quicksand? 23 --
Why do some mountain ranges look blue if they are covered with green forests? 25 --
How come there are deserts? 28 --
If the rivers drain into the oceans, why don't the oceans fill up and overflow? 33 --
How do islands form? 36 --
How do icebergs form? 38 --
What are the jet streams, and what causes them? 41 --
What causes the different shapes of clouds? 44 --
Why are rain clouds black in color? What happens to clouds after they form? 47 --
What causes the sound of thunder? 50 --
Why does a rainbow always form an arch? 52 --
What makes dew appear on grass? 54 --
What is the cause of fog? 56 --
Why do jet airplanes leave trails in the sky that look like clouds? 58 --
Why does the sky turn colors at sunset? 60 --
How is Earth like a magnet? 62 --
Is it true draining water swirls in opposite directions north and south of the equator? 65 --
Why do ships and planes disappear in the Bermuda Triangle? 67 --
Why do we seem to see a face in the Moon? 70 --
Why does Earth have only one moon? 72 --
How come Earth doesn't have any rings? 75 --
Where does dust come from? 77 --
How do fish breathe underwater? 80 --
How come fish and dolphins don't sleep? 83 --
Why do some sharks die if they stop swimming? 85 --
If whales can't walk, why do they have hips? 87 --
Do whales really sing? 89 --
Why are electric eels electrical? 92 --
How does a chameleon change its color? 95 --
How can a hummingbird fly both forward and backward? 98 --
How do birds know where south is? 101 --
Why are butterfly wings so colorful? 105 --
How come moths eat wool? 109 --
Where do bugs go in cold weather, reappearing like magic when it warms up? 112 --
How many eyes does a fly have? 115 --
How do you get lice, and how do you get rid of them? 117 --
Why do elephants have such big ears? 120 --
How can camels survive with little or no water? 122 --
Why does a porcupine have quills? How do they work? 124 --
Why do raccoons have black masks? 127 --
Do flying squirrels really exist? 129 --
How do cows digest their food? 131 --
Why do cats' eyes shine in the dark? 137 --
How do animals communicate without language? 140 --
How come so many animals have tails (and we don't)? 143 --
How did dinosaurs get their long and difficult names? 146 --
Why do animals become extinct? 149 --
Why do fingers get wrinkled after soaking in water for a long time? 154 --
Why do people get goose bumps? 157 --
Why do we get bruises? And why are they black and blue? 159 --
How does blood stop flowing out of a cut? 162 --
What makes your nose bleed? 165 --
How does hair grow? 167 --
Why does hair grow mostly on our heads? 169 --
Why do men seem to lose their hair more often than women do? 171 --
Why do we get pimples? 174 --
What causes warts? 176 --
What causes freckles? 178 --
Why does the sun make our skin darker, but our hair lighter? 180 --
Why and how do we get fevers? 183 --
Why do our ears pop when we fly on a plane or drive in the mountains? 186 --
Why do people sneeze? 189 --
What makes us allergic to things? 191 --
What causes an itch, and how come it feels better when you scratch it? 193 --
How does the nose smell things? 196 --
How come chopping onions makes you cry? 199 --
What gives foods their different tastes? 201 --
Why do our faces flush, eyes water, and noses run when we eat hot, spicy food? 203 --
What is cholesterol? 206 --
Why is cigarette smoking bad for the lungs? 209 --
How does alcohol affect the body? 212 --
Why does our breath smell bad, especially in the morning? 214 --
Why do people burp? 217 --
What makes your stomach growl? 219 --
How come acids in the stomach don't destroy it? 221 --
Do we really need an appendix? 224 --
Where do our voices come from? 226 --
Why do people snore? 228 --
Why do we need sleep? 230 --
Why do people sleepwalk? 232 --
What causes headaches? 234 --
How do muscles work, and how do you build muscle? 236 --
How does the heart work? 239 --
What is high blood pressure? 241 --
Why do we run out of breath when we run? 243 --
How does sweating work? 245 --
Where does the fat go when you lose weight? 248 --
What is the difference between identical and fraternal twins? 250 --
What makes our eyes the color they are? 252 --
Why do we giggle when we hear jokes? 254 --
Why do we sometimes feel that what we're experiencing has happened before? 258 --
Factory Field Trip 261 --
How is chewing gum made? 262 --
How is chocolate made? 264 --
How is decaffeinated coffee made? 266 --
Why does rubber bounce? 268 --
How is glass made? How is it shaped into drinking glasses and pop bottles? 270 --
What is perfume made of? And where do they come up with the fragrance names? 273 --
How are diamonds formed? 276 --
How do gems form and how do they get their color? 279 --
How does detergent get clothes clean? 284 --
How does a refrigerator work? 287 --
How does a microwave oven cook food? 289 --
How does a radio work? 292 --
How does a compact disc play music? 296 --
How does a mercury thermometer work? 298 --
How does hot air lift a balloon? 300 --
How do jet airplanes fly? 303 --
How is paper made? 306 --
How does glue work? 308 --
How does a magnifying glass work? 310 --
How does camera film record pictures? 313 --
How do electric lightbulbs emit light? 315 --
How does a telephone work? 318 --
How were mummies made? 321.
