The Great Expedition Series, Book 13

A Million Whys: The Light Expedition for Curious Kids

By Crafty Clover. Published by Million Whys Press.

Why Does Light Travel in Straight Lines? Why Can You See Yourself in a Mirror but Not in a Wall? Why Does a Laser Pointer Make a Tiny Dot Instead of a Wide Beam? This book answers 150 questions like these, one question per page, each with a short video answer. Six expeditions: Sunbeams & Shadows, Mixing Colors & Filters, Mirrors, Lenses & Bending Light, Shine, Matte & See-Through, Light Machines & Tricks, and Lamps, Lights & Safe Looking.

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All 150 questions

Tap a question to watch its video and read the answer.

Expedition 1: Sunbeams & Shadows

1. Why Does Light Travel in Straight Lines?
2. Why Is Light the Fastest Thing There Is?
3. Why Does Sunshine Take About Eight Minutes to Reach Earth?
4. Why Can You See a Sunbeam Streaming Through Dusty Air?
5. Why Are the Spots of Sunlight Under a Tree Round?
6. Why Can a Shadow Look Sharp One Minute and Fuzzy the Next?
7. Why Do You Get More than One Shadow Under Several Lamps?
8. Why Are Shadows on Snow Sometimes Blue?
9. Why Can a Flashlight and Your Hands Make a Shadow Animal?
10. Why Does a Glass of Water Throw a Bright, Wiggly Shadow?
11. Why Is It Cooler in the Shade than in the Sun?
12. Why Do Dark Clothes Feel Hotter in the Sun than Light Ones?
13. Why Does Sunshine Feel Warm on Your Face Even When the Air Is Cold?
14. Why Can a Cardboard Solar Oven Cook with Only Sunshine?
15. Why Does Snow Melt First Around a Dark Rock?
16. Why Do Houseplants Lean Toward a Window?
17. Why Does the Bright Patch From a Window Slide Across the Floor?
18. Why Is a Cloudy Day Outside Still Brighter than a Lit Room Inside?
19. Why Do Shadows Disappear on Cloudy Days?
20. Why Does Your Shadow Stretch, Shrink, and Stretch Again as You Walk Past a Streetlamp?
21. Why Does Your Hand Make a Giant Shadow When It Is Close to a Lamp?
22. Why Can You See the Shadow of a Cloud Sliding Across a Field?
23. Why Does Your Shadow Always Follow You?
24. Why Do Beams of Sunlight Fan Out From Behind a Cloud?
25. Why Do Tall Buildings Leave Long, Cool Shadows on City Streets?

Expedition 2: Mixing Colors & Filters

26. Why Do Red, Green, and Blue Lights Mix to Make White Light?
27. Why Do Paints Mix Differently From Colored Lights?
28. Why Can You Make Almost Any Color From Just Three Paints?
29. Why Does Mixing All Your Paints Make a Muddy Brown?
30. Why Does a Red Cellophane Sheet Change What You See?
31. Why Do Colors Look Different Under Different Lamps?
32. Why Do Some People See Some Colors Differently?
33. Why Do Screens Use Only Red, Green, and Blue Dots?
34. How Does the Color of Paper Change How Much Light Bounces Back?
35. Why Do Two Colored Flashlights Make Colored Shadows?
36. Why Does a Spinning Color Wheel Turn White?
37. Why Does the Same Gray Look Lighter or Darker on Different Backgrounds?
38. Why Do Secret Decoder Windows Reveal Hidden Messages?
39. Why Does Adding White Paint Make a Color Lighter?
40. Why Does Wet Sand Look Darker than Dry Sand?
41. Why Do Colors on a Phone Screen Look Different From Colors on Paper?
42. Why Are Roofs in Hot Places Often Painted White?
43. Why Do Old Posters in Sunny Windows Fade to Blue?
44. Why Do Magicians Hang Black Cloth Behind Their Tricks?
45. Why Can’t You Make Black by Mixing Colored Lights?
46. Why Do Newspaper Pictures Turn Into Tiny Dots Under a Magnifier?
47. Why Can Bees See Patterns on Flowers That We Cannot?
48. Why Does a Red Apple Look Almost Black Under a Green Light?
49. Why Do Artists Use a Color Wheel to Pick Colors That Look Good Together?
50. Why Does Paint Change Color a Little as It Dries?

Expedition 3: Mirrors, Lenses & Bending Light

51. Why Can You See Yourself in a Mirror but Not in a Wall?
52. Why Does Light Bounce Off a Mirror at the Same Angle It Hits?
53. Why Can a Periscope Let You See Over a Wall?
54. Why Do Two Mirrors Facing Each Other Show Endless Copies?
55. Why Does Your Face Look Upside Down in the Back of a Spoon?
56. Why Do Car Side Mirrors Say Objects Are Closer than They Appear?
57. Why Does a Makeup Mirror Make Your Face Look Bigger?
58. Why Does a Swimming Pool Look Shallower than It Really Is?
59. Why Does a Coin Appear When You Pour Water Into a Bowl?
60. Why Does a Glass of Water Flip an Arrow Upside Down?
61. Why Does a Magnifying Glass Make Things Look Bigger?
62. Why Should You Never Play with a Magnifying Glass in the Sun?
63. Why Do Some Lenses Make Things Look Smaller?
64. Why Can a Water Drop on a Leaf Work Like a Tiny Lens?
65. How Does a Microscope Show Things Too Small to See?
66. Why Is the Word Ambulance Written Backward on the Front of the Van?
67. Why Can You See Your Room Reflected in a Window at Night?
68. Why Can Some Windows Look Like Mirrors From the Outside in the Daytime?
69. Why Does a Calm Lake Show a Mirror Picture and a Windy Lake Does Not?
70. Why Do Things Look Bigger and Closer Underwater?
71. Why Does a Lens Bring Light Together at One Spot?
72. Why Does a Kaleidoscope Make Endless Patterns?
73. Why Do Funhouse Mirrors Make You Look Wide or Skinny?
74. Why Do You Only Need a Half-Length Mirror to See Your Whole Body?
75. Why Do Shiny Round Balls Show the Whole Room in a Tiny Picture?

Expedition 4: Shine, Matte & See-Through

76. Why Can You See Through Glass but Not Through Wood?
77. Why Does Frosted Glass Hide Shapes but Still Let Light In?
78. Why Does a Sheet of Paper Glow When You Hold a Flashlight Behind It?
79. Why Does Wet Paper Turn See-Through?
80. Why Are Some Things Shiny and Others Dull?
81. Why Are Metals So Shiny?
82. Why Does Polishing Make a Spoon Shinier?
83. Why Do Air Bubbles in Water Look Silvery?
84. Why Does Frost Sparkle?
85. Why Do Gemstones Sparkle More When They Are Cut?
86. Why Do Glitter and Sequins Flash When You Move?
87. Why Do CDs and DVDs Shimmer with Colors?
88. Why Does the Inside of a Seashell Shimmer with Colors?
89. Why Does a Wet Leaf Look Shinier than a Dry One?
90. Why Does Glare Make a Shiny Page Hard to Read?
91. Why Do Phone Screens Turn Into Mirrors in Bright Sunshine?
92. Why Can a Pond Look Like a Mirror When You Look From Low Down?
93. Why Is Muddy Water Cloudy?
94. Why Does Milk Look White When Water Is Clear?
95. Why Is the Foam on a Dark Drink White?
96. Why Is Table Salt White When One Crystal Is Clear?
97. Why Are Some Plastics Clear and Others Cloudy?
98. Why Do Some Windows Have a Thin, Shiny Coating?
99. Why Does Crinkled Foil Sparkle in Every Direction?
100. Why Do Very Dark Materials Like Velvet Seem to Swallow Light?

Expedition 5: Light Machines & Tricks

101. Why Does a Laser Pointer Make a Tiny Dot Instead of a Wide Beam?
102. Why Must You Never Shine a Laser Pointer at Anyone's Eyes, a Plane, or an Animal?
103. Why Does a Projector Turn a Tiny Picture Into a Huge One?
104. Why Does a Flip Book Make Pictures Move?
105. Why Do Hologram Stickers Change as You Tilt Them?
106. How Do Optical Fibers Trap Light Inside a Thread?
107. What Is Infrared Light, and Why Can We Feel It but Not See It?
108. Why Do Streetlights Switch on by Themselves at Dusk?
109. How Does a Solar-Powered Calculator Work Without a Battery?
110. Why Can One Tiny LED Shine Red, Green, or Blue?
111. Why Does a Flashlight Beam Get Wider the Farther It Goes?
112. Why Does a Flashlight Have a Shiny Cup Behind the Bulb?
113. Why Does a Mirror Ball Scatter Dots of Light Around a Room?
114. Why Do 3-D Glasses Make Pictures Seem to Pop Out?
115. Why Do Some Screens Go Dark When You Tilt Polarized Glasses?
116. Why Do Magicians' Mirror Tricks Fool Our Eyes?
117. Why Does the Same Line Look Longer with Arrowheads on the Ends?
118. Why Can a Laser Measure How Far Away a Wall Is?
119. Why Can a Scanner Copy a Picture Using a Moving Line of Light?
120. Why Do Indoor Plant Lamps Often Look Pink or Purple?
121. Why Do Some Solar Power Plants Use Hundreds of Mirrors?
122. Why Does a Lamp Look Dimmer the Farther Away It Is?
123. Why Can a Laser Read the Tiny Bumps on a Disc?
124. Why Do Neon Signs Glow?
125. How Can a Small Mirror Flash a Signal Across a Valley?

Expedition 6: Lamps, Lights & Safe Looking

126. Why Do Bike Reflectors Shine When a Car's Headlights Hit Them?
127. Why Do Crossing Guards and Road Workers Wear Bright Vests?
128. Why Do Bikes Need a White Light in Front and a Red Light in Back?
129. Why Does a Flashlight Look Weaker in Fog or Rain?
130. Why Do Some Lamps Look Warm and Yellow While Others Look Cool and White?
131. Why Does a Flashlight Get Dimmer as Its Batteries Run Down?
132. Why Is It Easier to Read When a Lamp Shines on the Page?
133. Why Should You Never Look Straight Into Very Bright Lights?
134. Why Do Night-Lights Stay Dim on Purpose?
135. Why Do Exit Signs Stay Lit Even When the Power Goes Out?
136. Why Do Drivers Switch Off Their High Beams for Oncoming Cars?
137. Why Do Airplanes and Boats Have Red and Green Lights?
138. Why Do Tall Towers Have Blinking Red Lights?
139. Why Are Tunnels Extra Bright Near the Entrance?
140. Why Do Window Blinds Control How Much Light Comes In?
141. Why Do Lamps Have Shades?
142. What Is Ultraviolet Light, and Why Can't We See It?
143. Why Are Special Eclipse Glasses Safe When Ordinary Sunglasses Are Not?
144. Why Are Old Paintings and Photographs Kept in Dim Light?
145. Why Are Brake Lights Red?
146. Why Do Emergency Vehicles Flash Red and Blue Lights?
147. Why Should You Keep Paper and Curtains Away From Hot Lamps?
148. Why Can You See a Line of Light Under a Closed Door?
149. Why Do Some Athletes Put Dark Marks Under Their Eyes?
150. What Is Light Really Made Of?