Book 3 activities
Try it at home: 150 science activities from Book 3
Every question in A Million Whys Book 3, The Built Expedition, ends with a "Think like a scientist" idea. Here they are in one place. Each one links to its question page, with the video and the full answer.
Questions 1 to 25 (25)
1. Why Do Bikes Stay Up When You Ride?
First, with a grown-up, hold a bike still. Then roll it forward slowly, and keep holding on. Feel when it wants to tip, and when it feels steady. Which felt steadier, still or rolling? Why do you think so?
Do this with a grown-up2. Why Do Airplanes Stay in the Sky?
First, fold two paper planes that are exactly the same. Next, gently curve the wings of one plane. Then ask, which one glides farther? And ask a grown-up to come along if you throw them outside! Paper planes make a great test, because you can change one thing at a time.
Do this with a grown-up3. Why Do Boats Float?
Try this in a sink. Make a clay ball, and make a clay boat. Use the same clay, but a different shape. Which one floats, and why do you think so? Keep a grown-up nearby around the water.
Do this with a grown-up4. Why Do Wheels Beat Dragging?
First, push a heavy book across a table. Next, put two round pencils under it and push again. Which one is easier, and why do you think so? Keep a grown-up nearby. Those pencils are acting just like tiny wheels!
Do this with a grown-up5. Why Do Paper Airplanes Fly?
First, fold two paper planes. Next, put a paper clip on the nose of one plane. Which one flies straighter, and why do you think so? If you throw them outside, bring a grown-up. Change only one thing at a time, so you know what made the difference.
Do this with a grown-up6. Why Do Trains Need Tracks?
First, roll a toy car across a carpet. Next, roll it along a smooth ruler. Which one goes farther, and why do you think so? Notice how much less rubbing the smooth path has! Smooth surfaces are great for rolling, and rough ones slow things down.
7. Why Do Helicopters Hover?
With a grown-up, watch a helicopter takeoff video. Look closely at the blades. Can you see how they tilt? Which way does the helicopter move when they tilt? Write down what you notice!
Do this with a grown-up8. Why Do Cars Need Brakes?
Try a friction test. First, rub your hands together fast. Next, feel how warm they get. That warmth is friction, the same thing that helps brakes stop a car. And keep a grown-up nearby for any car or bike brake test.
Do this with a grown-up9. Why Is a Ship Pointed in Front?
First, with a grown-up, fill a sink with water. Push the pointed end of a spoon through it. Next, push a wood block through the water. Which one is easier, and why? Remember to keep a grown-up nearby around the water.
Do this with a grown-up10. Why Do Hot Air Balloons Go Up?
With a grown-up, watch steam rise from a mug of warm water. See how the warm steam rises up? A chimney's smoke rises for the same reason. But only look, and keep a grown-up close if it is hot.
Do this with a grown-up11. Why Do Tires Have Treads?
First, wipe a wet plate with the bottom of a cup. Then wipe the same wet plate with a fork. The fork leaves channels, just like tire tread. Which one clears water better, and why? Try to picture how the water squeezes out.
12. Why Do Planes Have Flaps?
With a grown-up, watch a plane land, in person or in a video. Look at the back of the wing. Can you see the flaps move down? And if you fly someday, sit over the wing to watch them move! Many small planes have flaps too.
Do this with a grown-up13. Why Do Submarines Sink and Rise?
First, a closed empty bottle floats in a tub. Next, add some water, and it sinks. Never try this in a pool without a grown-up. Always keep a grown-up nearby. That is a great way to see ballast at work.
Do this with a grown-up14. Why Do Bikes Have Gears?
With a grown-up, ride on a safe path. Click the gears one at a time. Feel how pedaling gets easier or harder. Which gear feels easiest on a hill? Always ride safely!
Do this with a grown-up15. Why Do Rockets Need Fire?
First, blow up a balloon and pinch it closed. Next, let it go. Air goes one way, and the balloon goes the other. Grown-up nearby for any rocket play. Which way does the balloon zoom?
Do this with a grown-up16. Why Do Cars Have Seatbelts?
With a grown-up, gently roll a toy car with a clay rider. Try it with no belt, then with a rubber band belt, into a pillow. Which rider stays put? And write down what you see. This is a safe way to see the idea.
Do this with a grown-up17. Why Do Airplanes Have Propellers?
First, fold a paper airplane. Then blow toward the tail, using a handheld toy fan. Feel the push? Keep a grown-up nearby for any spinning toys. Small experiments show big ideas.
Do this with a grown-up18. Why Do Sailboats Need Wind?
In a sink, float a cork with a paper sail. Blow from different sides. When does it go forward, and when does it just tip? Keep a grown-up nearby around water. Small sails teach big ideas.
Do this with a grown-up19. Why Do Skateboards Roll?
First, roll a toy car across the floor. Then drag the same toy on its side. Which one takes less effort? That is rolling versus sliding. Watch how easily the toy rolls.
20. Why Do Parachutes Work?
First, drop two identical toys. Tape a napkin parachute to one of them. Which one lands last? Then try bigger and smaller napkins. Test it with a few different sizes.
21. Why Do Trucks Have So Many Wheels?
First, press just a fingertip into some clay. Then press with the back of a spoon. Which dent is deeper? That difference is pressure. Notice how pressure changes with size.
22. Why Do Gliders Fly with No Engine?
First, fold two paper planes. Give one of them longer wings. Now launch both gently from a chair. Try it three times, and compare which one glides farther. Look at how the wing length changes things.
23. Why Do Cars Have Headlights?
In a dim room with a grown-up, shine a flashlight through clear tape. Then shine it through dusty tape on glass. Which beam is stronger? And never look straight into the light. Compare them side by side.
Do this with a grown-up24. Why Do Tunnels Go Through Mountains?
With a grown-up nearby, build two paths in sand. One goes over a hill of cups. The other goes through a paper tube tunnel. Which toy car gets there faster? Compare the two paths.
Do this with a grown-up25. Why Do Boats Have Rudders?
First, float a toy boat. Tape a popsicle stick rudder to the back. Blow the boat forward, and twist the stick. Which way does the bow go? Write down what you notice.
Questions 26 to 50 (25)
26. Why Do Lights Turn on with a Switch?
With a grown-up, connect a battery pack, a small bulb, and a paper clip. That clip is your switch. When the clip touches both wires, the bulb should glow. Why does the bulb go out when you move the clip away? A simple test can show big science.
Do this with a grown-up27. Why Do Batteries Die?
With a grown-up, time how long a new battery runs a small toy. Then time a used battery in the same toy. Write down both times. Which one lasted longer, and why do you think so? That is called collecting data.
Do this with a grown-up28. Why Is Fire Hot?
With a grown-up, watch a candle burn. Where is the flame brightest? What happens if the grown-up gently covers it with a glass? And remember, do not touch the flame. This shows why fire needs air.
Do this with a grown-up29. Why Do Magnets Stick?
Test what a fridge magnet can pick up. Try paper, a coin, a key, and some plastic. Make a yes or no table. What do the things that stick have in common? Pay attention to what is made of iron.
30. Why Do Solar Panels Work?
Put a solar toy or calculator in the sun. Then move it into the shade. What happens to the toy? Why do you think that happens? Light matters a lot for solar power.
31. Why Do We See Lightning Before Thunder?
With a grown-up, watch from a window. Count the seconds from the flash to the boom. Track three flashes. Is the storm getting closer or farther? Write down your numbers.
Do this with a grown-up32. Why Does Static Make Hair Stick Up?
Rub a balloon on your shirt. Hold it near tiny bits of paper. Do the paper bits jump? Why do you think so? Watch what happens closely.
33. Why Do Phones Need Charging?
With a grown-up, note the battery percent in the morning. Then note it again at bedtime, for two days. Which day used more battery power? What did you do differently? Comparing days is a great experiment.
Do this with a grown-up34. Why Do Light Bulbs Get Warm?
With a grown-up, feel the air near an LED lamp after one minute. Then feel the air near an older bulb. Which one is warmer? And do not touch the bulbs themselves. Remember to be careful around hot things.
Do this with a grown-up35. Why Does Ice Melt?
Let us time two ice cubes. Put one on a plate. Wrap the other in a towel. Which one lasts longer, and why? Keep a grown-up nearby around stoves.
Do this with a grown-up36. Why Do Fans Cool Us?
Wet a finger. Hold it in still air. Then hold it in front of a fan. Which one dries faster? Ask a grown-up to be nearby.
Do this with a grown-up37. Why Is a Toaster Hot?
With a grown-up, toast one slice of bread on low. Then toast another slice on high. Compare the color and the time. And do not touch the coils! Always ask a grown-up to help.
Do this with a grown-up38. Why Does a Kettle Whistle?
With a grown-up, watch a kettle from a safe distance. Look for the first bubbles. When does the sound start, compared with the first bubbles? And never lean over steam. That's how scientists find out what happens first.
Do this with a grown-up39. Why Do Fireworks Have Colors?
At a public fireworks show, watch from a safe distance with a grown-up. Make a tally mark for every color you see. Which color showed up most? Guess which metal made it! Ear protection helps. And never pick up a dud!
Do this with a grown-up40. Why Does a Compass Point North?
Place a compass on a table, and keep it level. Slowly bring a fridge magnet close to the compass. Then take the magnet away. What happens to the needle? Can you explain why?
41. Why Does a Microwave Heat Food?
With a grown-up, fill two cups. Put water in one, and dry rice in the other. Heat them for just a few seconds. Then carefully feel them. Go slow, because they can be hot! Which one feels warmer? Think about where the water is!
Do this with a grown-up42. Why Do LED Lights Use Less Power?
With a grown-up, find an LED lamp and an old-style bulb. Let each one shine for one minute. Then carefully feel each one. Be gentle, because bulbs can be hot! Which one wastes more heat? Why do you think so?
Do this with a grown-up43. Why Does Rubbing Hands Make Heat?
Rub your hands together 10 times, nice and slow. Then rub your hands 10 times, nice and fast. Which one felt warmer? Why do you think so? Write down what you notice, like a real scientist!
44. Why Does Steam Rise?
With a grown-up, watch a hot mug from the side. Where does the wisp go first: up, sideways, or down? Keep a safe distance, and never lean over the steam. Why do you think it goes that way?
Do this with a grown-up45. Why Do Plugs Have Three Prongs?
With a grown-up, count the plugs at home. How many have two prongs? How many have three? Write it down! Remember, wet hands and outlets do not mix!
Do this with a grown-up46. Why Do Power Lines Hum?
Stand outside with a grown-up, near a safe sidewalk. Listen carefully. Can you hear a hum? Try again after it rains. Does the hum change? And never climb a pole!
Do this with a grown-up47. Why Does a Fridge Stay Cold?
Carefully feel the coils on the back of a fridge, not the dusty floor. Ask a grown-up to help you. Do the coils feel warmer than the room? Where do you think that heat came from?
Do this with a grown-up48. Why Do Shadows Happen?
Make a shadow with a flashlight and a toy. Move the toy closer to the wall. What happens to the size of the shadow? Then try moving the light. Write down what you see!
49. Why Is the Sun So Bright?
On a bright day, go outside with a grown-up. Compare the shade and the sun on the back of your hand, for two seconds. Which feels stronger? And look away from the Sun itself!
Do this with a grown-up50. Why Does a Candle Melt?
With a grown-up, watch a candle burn. Watch where the first puddle forms. Is it at the top, the middle, or the bottom? And stay safe around flames!
Do this with a grown-upQuestions 51 to 75 (25)
51. Why Do Buildings Have Foundations?
Stand a cardboard box on four pencils. Then stand the same box on a wide book. Gently poke each one. Which base tips less? Why do you think so?
52. Why Do Bridges Have Arches?
Lean two books together, to make a tent. Gently press on the peak. Feel how the bottoms want to slide out. That sideways push is what an abutment stops!
53. Why Do Skyscrapers Sway?
Hold a ruler upright on a table, and blow on it. Then tape a coin near the top, and blow again. Watch how each one wobbles. Which one wobbles less? Why do you think so?
54. Why Is Concrete So Strong?
Mix a spoon of flour, sand, and a few drops of water. Let it dry overnight. Does it hold together better than dry sand alone? Write down what you observe, like a real scientist!
55. Why Do Houses Have Sloped Roofs?
Fold a paper into a steep tent, and another sheet flat. Sprinkle water on both. Which one keeps the table underneath drier? Why do you think that happened?
56. Why Do Windows Have Glass?
Hold clear plastic wrap up to a lamp. Then hold up a piece of cardboard. Which one lights the table? And which one makes a shadow?
Do this with a grown-up57. Why Do Doors Have Hinges?
Tape a book to a cereal box, with one piece of tape as a hinge. Swing the book open and shut. Then try lifting the book off every time. Which is easier? Why do you think so?
58. Why Do Stairs Have Railings?
Walk along a low curb, with your arms out. Then walk with one hand on a wall. Which way feels safer? Try stairs with a grown-up nearby.
Do this with a grown-up59. Why Do Chimneys Go Up?
With a grown-up watching, hold a pinwheel above a warm lamp. Then hold it beside the lamp. Which spot makes it spin? That's because heat rises!
Do this with a grown-up60. Why Do Buildings Have Elevators?
Hang a small bag of books over a broom handle, with string. Hang a second bag of similar weight on the other side. Then try lifting one side. Which side is easier to lift? Why?
61. Why Do Suspension Bridges Use Cables?
Hang a string between two chairs. Clip paper clips along the string. Does the string sag more as you add clips? That's what the towers and anchors fight!
62. Why Do Tunnels Have Lining?
Push a paper-towel tube into a pile of sand. Then carefully pull the tube out. Does the hole collapse? A lining is the tube you leave behind!
63. Why Do Walls Use Bricks?
Stack crackers with the seams lined up. Then stack more, with the seams not lined up. Give each tower a gentle nudge. Which tower twists less?
64. Why Do Roofs Have Gutters?
Pour water down a cookie sheet, into a cereal box channel. Now tilt the channel. Does the water pick a direction? Why do you think it does?
Do this with a grown-up65. Why Do Buildings Have Insulation?
Wrap one cup of warm water in a towel. Leave another cup bare. Wait ten minutes. Which stays warm longer? Why?
66. Why Can Cranes Lift So Much?
Balance a ruler on a pencil. Put a lump of clay near one end. Put a coin far out on the other end. Which side acts like the counterweight?
67. Why Do Dams Hold Back Water?
Hold a plastic bag of water. Squeeze the bottom, and then the top. Where does it feel stronger? That's why dams are thicker at the bottom!
68. Why Do Lighthouses Flash?
Shine a flashlight through a magnifying glass onto a wall. Watch the spot of light. Does the spot get brighter and smaller? That's a simple lens beam!
69. Why Do Stadiums Have Huge Roofs?
Hold a sheet of paper between two books. Then fold it into a pleated paper fan. Which one sags less in the middle? Folds work just like trusses!
70. Why Do Towers Stay Standing?
Stand a paper-towel tube on end, and blow. Then tape a wide card under it, as a base. Blow again. Which one tips first?
71. Why Do Floors Have Beams?
Rest a ruler on two cups, and press the middle. Then stand the ruler on its edge, and press again. Which way bends less? Why do you think so?
72. Why Do Cities Have Sewers?
Tilt a tray of water, with a drop of food coloring. Watch the color. Does the color always run downhill? Gravity is the sewer's engine!
73. Why Do Sidewalks Crack?
Let mud dry in a pie tin. Wait until it dries. Do cracks appear? That's shrink-and-split, the same family as sidewalk cracks!
74. Why Do Pyramids Last So Long?
Stack cups into a pyramid. Then stack cups into a tall, single column. Blow on both. Which one falls first?
75. Why Do Buildings Need Doors That Open?
Stand in a doorway, and feel the air. Then close the door. On a cold day, which way keeps the room warmer? Why do you think so?
Questions 76 to 100 (25)
76. Why Do Phones Ring?
With a grown-up, set two phones across a room. Call one of them. Which arrives first: the sound in the air, or the buzz in your hand? Radio waves travel at the speed of light, and beat slow sound!
Do this with a grown-up77. Why Does Email Arrive So Fast?
Let's have a race. First, time how long a paper note takes to walk across a room. Next, send a one-word email to a grown-up, and time that too. Which letter wins the race? And why do you think so?
Do this with a grown-up78. Why Do Radios Play Music From Far Away?
Let's tune in. Tune a portable radio in a basement, then again near a window. Where is the song stronger? Walls block some waves. Can you find the spot with the best signal?
79. Why Do Cameras Take Pictures?
Let's make a pinhole camera. With a grown-up's help, poke a tiny hole in a box. Point the hole at a bright window. Look at the opposite inside wall. Do you see a dim, upside-down scene?
Do this with a grown-up80. Why Do Clocks Keep Time?
Be a clock. Count one-Mississippi for 60 seconds while a grown-up watches a phone timer. How close were you? Try it again. Your body is a rough clock!
Do this with a grown-up81. Why Do Computers Need Programs?
Be a programmer. Write 3 steps for making a sandwich on sticky notes. Ask a friend to follow them exactly. Did your program miss a step? Fix it, and try again!
82. Why Does Wi-Fi Have No Wires?
Test your signal. Check your Wi-Fi in the same room as the router. Then walk behind a closed door and check again. Obstacles eat radio waves. Is the signal weaker? Why?
83. Why Do Barcodes Beep at the Store?
Make a secret code. Draw thick and thin marker lines on paper. Agree with a friend on a secret pattern of ones and zeros first. Can your friend decode it? How is that like a barcode?
84. Why Do TVs Show Moving Pictures?
Make a flipbook. Draw a stick figure on sticky notes, changing it a little each page. Stack them and flip the pages. How fast must you flip to make the figure walk? What happens if you flip slowly?
85. Why Do Speakers Make Sound?
Let's feel some sound. Play some music, and gently rest a fingertip on the speaker grill, not the cone. Can you feel the buzz? That motion is the sound. Try a low note and a high note. What changes?
86. Why Do Keyboards Have Letters?
Let's have a contest. Time how long it takes to write your name with a pencil. Then time how long it takes to type it. Which tool wins? And why do you think so?
87. Why Do Printers Put Ink on Paper?
Watch dots spread. With a grown-up's help, press a washable marker onto paper. Then spray a little water mist nearby. Do the dots spread out? Printers control spread by using tiny drops.
Do this with a grown-up88. Why Do Satellites Help Phones?
Be a satellite. Shine a flashlight at a tilted mirror. Bounce the spot of light across the room. That bounce is a simple relay. Can you make it land on a target?
89. Why Does GPS Know Where You Are?
Play the GPS game. Have three friends each hold a string tied to the same toy. Each friend stands far away from the others. Where all the strings pull tight is like a GPS fix. Can you find the toy from the strings alone?
90. Why Do Traffic Lights Change?
Time a real light. With a grown-up, time how many seconds a light stays green. Then time how many seconds it stays red. Which is longer? Is it fair for the busier street?
Do this with a grown-up91. Why Do Doorbells Ring?
Listen to your doorbell. With a grown-up, listen to the notes your doorbell plays. Is the sound made by a chime or by a speaker? What happens if you press the button twice, quickly? Write down what you notice.
Do this with a grown-up92. Why Did Morse Code Use Dots and Dashes?
Send a secret message. Tap SOS on a table. Have a friend decode your taps without you speaking. Then spell your initials in Morse code. Which letters take the most taps?
93. Why Do QR Codes Hold So Much?
Test a QR code. Find a QR code on a box or a sign. Cover one corner with your finger and try to scan it. Then cover the center instead. Why are the corner squares so important?
94. Why Do Microphones Pick Up Voices?
Test a phone mic. Hum the same note close to a phone, then far away. If you can record it, watch the waveform. Does the volume change? Why would a singer stand a hand-width from the mic?
95. Why Do Headphones Work?
Compare how you hear. Play a song on speakers, then listen with headphones. Which sounds closer to your ears? Now cup your hands over your ears. What changes?
96. Why Do Video Calls Show Faces Far Away?
Test the lag. Start a video call with a grown-up in another room. Wave, and count how long until they wave back. Then ask a grown-up to turn off the Wi-Fi. What happens to the call?
Do this with a grown-up97. Why Do Robots Follow Instructions?
Be a robot. Write 3 simple steps for a friend: walk, turn, and stop. Your friend must follow them exactly, like a robot. Did it work? How exact must a programmer be?
98. Why Do Remote Controls Work?
Spy on the light. Point a remote at a phone camera, and press a button. Do you see a flashing purple-white light? Now put a book in the way. Does the signal pass through?
99. Why Do Smoke Alarms Beep?
Always with a grown-up. Ask a grown-up to press the test button. How many beeps do you count? Now look at the vents. Why must air be able to float inside?
Do this with a grown-up100. Why Do Passwords Exist?
Compare two pretend passwords. Make up two pretend passwords: the short word sun, and a long, mixed one with a flower and numbers. Which would take a guessing robot longer to try? Why is a long sentence often stronger than one short word? Never use your real password for this!
Questions 101 to 125 (25)
101. Why Does a Ball Bounce?
Drop a ball twice. Drop a ball on a hard tile floor. Then drop it on a soft rug. Which bounce is taller? Why might a soft floor steal more of the spring?
102. Why Can You Ride a Bike Without Falling?
Feel a spinning wheel. With a grown-up, hold a bicycle wheel by the axle and spin it. Try to tilt it. Can you feel it resist? Then walk a bike slowly, and ride it faster with a grown-up nearby. When is the wobble worse?
Do this with a grown-up103. Why Do Swim Goggles Keep Water Out?
Always with a grown-up. Press dry goggles onto a plate of water. Does the seal hold a little air bubble? Now try one hair under the gasket. What happens to the seal?
Do this with a grown-up104. Why Does a Bat Have a Sweet Spot?
Find a sweet spot. Ask a grown-up to help. Hold a wooden spoon by the handle. Tap it at different spots. Where does your hand feel the least buzz? That quiet place is a cousin of the sweet spot.
Do this with a grown-up105. Why Is a Soccer Ball Made of Panels?
Count and wrap. Count the black pentagons on a classic soccer ball. Can you wrap a gift with one flat sheet and no folds? It gets wrinkly on a round shape. Why do panels help?
106. Why Does a Whistle Get So Loud?
Compare two sounds. Blow across a bottle top, then blow into a whistle. Which sound carries farther across a room? What did the chamber add? Clean the whistle before anyone else uses it.
107. Why Do Drums Boom?
Compare two booms. Tap an empty tin can, and then a full backpack. Which sound is bigger and deeper? Why does an empty space help the sound? Use gentle taps, please!
108. Why Does Tightening a Guitar String Raise the Pitch?
Use a rubber band. Stretch a rubber band between two fingers and pluck it. Now stretch it tighter. Did the note rise? Try a thicker band. What changed?
109. Why Does an Echo Come Back?
Clap in two places. With a grown-up nearby, clap in a closet full of coats. Then clap in an empty hallway. Which sound lasts longer? Which surfaces stole the bounce?
Do this with a grown-up110. Why Do Ice Skates Glide?
Slide a coin. Ask a grown-up to help. Slide a coin across a table. Then slide it across an ice cube on a plate. Which trip is longer? Why might a bigger contact patch stick more?
Do this with a grown-up111. Why Does a Frisbee Fly?
Play outdoors with a grown-up. Throw one disc with lots of spin. Throw one with very little spin. Which flies flatter? What does the spin protect?
Do this with a grown-up112. Why Does a Swing Go Higher If You Pump?
Play with a grown-up nearby. Pump for 5 passes, and count each one out loud. Then sit still for 5 passes. When does the height fade? What force is stealing energy?
Do this with a grown-up113. Why Do Helmets Have Foam?
Do this with a grown-up, outdoors. Drop a raw egg in a box of packing foam. Drop another egg with no foam. Which raw egg stays in one piece? What did the foam change about the stop?
Do this with a grown-up114. Why Does a Yo-Yo Come Back?
First, wind the string tight around the axle, and throw the yo-yo. Then wind the string loosely, and throw it again. Which one sleeps at the bottom? And what did the loop change? Scientists always write down what they see. Have fun!
115. Why Do Bubbles Shimmer Then Pop?
Blow two bubbles, one in still air and one near a fan, with a grown-up to help. Watch which one lasts longer. Did the wind, the dry air, or both steal the water? Write down what you see! Scientists always write down what they see. Have fun!
Do this with a grown-up116. Why Does a Kite Need Wind?
On a gentle-breeze day, try a kite with a tail and one without, in an open field with a grown-up. Which one stays facing the wind? What job did the tail do? Write down what you notice! Scientists always write down what they see. Have fun!
Do this with a grown-up117. Why Do Sneakers Grip the Ground?
Slide a sneaker and a hard dress shoe across a dry board, then a damp board, with a grown-up. Which pair wins on the wet board? What did the tread change? Write down what you learn! Scientists always write down what they see. Have fun!
Do this with a grown-up118. Why Does a Jump Rope Need a Rhythm?
Jump to a slow clap, then to a fast clap, in an open space with a grown-up. When does the rope start clipping your toes? What did the beat control? Write down what you notice! Scientists always write down what they see. Have fun!
Do this with a grown-up119. Why Do Bowling Balls Have Finger Holes?
Compare holding a smooth orange and a mug with a handle, with a grown-up to help. Which one is easier to swing and let go? What job did the holes do? Write down what you notice! Scientists always write down what they see. Have fun!
Do this with a grown-up120. Why Does a Basketball Have Black Lines?
Try a set shot with your fingers on a seam, then on a smooth patch, in a driveway or gym with a grown-up. Which spin was easier to control? What did the ridge do? Write down what you notice! Scientists always write down what they see. Have fun!
Do this with a grown-up121. Why Do Referees Use Whistles?
Have a grown-up call 'stop' from across a yard, then use one short whistle. Which cue did you notice first? Why might a thin, high note win over a shout? Write down what you notice! Scientists always write down what they see. Have fun!
Do this with a grown-up122. Why Does a Trombone Note Drop When the Slide Moves Out?
Hum into a cardboard tube, then tape on a second tube, with a grown-up to help. Did your hum sound lower? What did the extra length change? Write down what you hear! Scientists always write down what they see. Have fun! Then share what you found with a friend or a grown-up.
Do this with a grown-up123. Why Do Marching Bands Stay in Step?
Walk across a room to a slow clap, then a fast clap, with a friend, in an indoor hallway with a grown-up. When did your steps match? What was the shared clock? Write down what you notice! Scientists always write down what they see. Have fun!
Do this with a grown-up124. Why Does a Playground Slide Feel Fast?
Race a block down a book ramp, then raise the book, on a table with a grown-up. Did the steeper ramp win? What did the extra height change into? Write down what you notice! Scientists always write down what they see. Have fun!
Do this with a grown-up125. Why Do Team Jerseys Have Numbers?
Write two names and two giant numbers on cards. Have a friend hold them across a room. Which could you read first? Why do digits beat curly letters at a distance? Scientists always write down what they see. Have fun!
Questions 126 to 150 (25)
126. Why Does a Hammer Have a Heavy Head?
Tap a tack into scrap wood with a spoon, then with a small metal wrench, with a grown-up to help. Which one sinks it more easily? What did the extra mass change? Write down what you notice! Scientists always write down what they see. Have fun!
Do this with a grown-up127. Why Is a Screwdriver Shaped Like That?
Try turning a toy screw with a coin, and then with a real screwdriver, with a grown-up to help. Which one slips less? What did the matching tip do? Write down what you notice! Scientists always write down what they see. Have fun! Then share what you found with a friend or a grown-up.
Do this with a grown-up128. Why Do Scissors Have Two Blades?
Cut scrap paper with two-blade scissors, and then try tearing the same paper by hand, with a grown-up to help. Which edge is cleaner? What did the passing blades add? Write down what you notice! Scientists always write down what they see. Have fun! Then share what you found with a friend or a grown-up.
Do this with a grown-up129. Why Does Glue Stick?
Glue two paper scraps and two shiny plastic scraps with school glue, with a grown-up nearby. Which pair peels apart first when dry? What did the paper pores add? Write down what you notice! Scientists always write down what they see. Have fun! Then share what you found with a friend or a grown-up.
Do this with a grown-up130. Why Does Tape Have Two Sides That Feel Different?
Touch both faces of a tape scrap, with a grown-up to help. Which face clings to a shirt? What job did the other face do? Write down what you notice! Scientists always write down what they see. Have fun! Then share what you found with a friend or a grown-up.
Do this with a grown-up131. Why Do Nails Have Points and Screws Have Threads?
Look at a nail and a screw with a grown-up. Which one has a ramp wrapped around it? Which one is mostly a wedge? Write down what you notice, and become a fastener expert! Scientists always write down what they see. Have fun!
Do this with a grown-up132. Why Does Sandpaper Scratch?
Rub scrap wood with coarse paper, and then with fine paper, with a grown-up to help. Which dust is chunkier? What did the tooth size change? Write down what you notice! Scientists always write down what they see. Have fun! Then share what you found with a friend or a grown-up.
Do this with a grown-up133. Why Does a Measuring Tape Roll Back Up?
Pull a badge reel or a tape a short way, and feel the tug, with a grown-up nearby. Where is the hidden spring working? What happens if you hold the lock? Write down what you feel! Scientists always write down what they see. Have fun!
Do this with a grown-up134. Why Do Magnets Pick Up Only Some Metals?
Test a fridge magnet on a spoon, a penny, foil, and a key, with a grown-up. Which objects move? What family of metals did the winners share? Write down what you find! Scientists always write down what they see. Have fun!
Do this with a grown-up135. Why Does a Level Have a Bubble?
Rest a clear bottle with a small air bubble on a table, then slip a book under one end, with a grown-up. Which way does the bubble run? Why does it chase the high side? Write down what you notice! Scientists always write down what they see. Have fun!
Do this with a grown-up136. Why Do Factories Use Conveyor Belts?
Line up toy cars on a towel, and pull the towel slowly, on a table with a grown-up. Did every car travel the same path? How is the towel like a conveyor belt? Write down what you notice! Scientists always write down what they see. Have fun!
Do this with a grown-up137. Why Do Bakers Weigh Instead of Just Scoop?
Scoop two cups of flour, one fluffed and one packed, with a grown-up in the kitchen. Then weigh both of them. Did the cups match? Why did the scale disagree with the cup? Write down what you learned. Happy baking! Then share what you found with a friend or a grown-up.
Do this with a grown-up138. Why Does a Sewing Machine Make a Lockstitch?
Look at the back of a store-bought seam, and a hand running stitch, with a grown-up. Which one looks like two threads hugging? What would happen if one thread were missing? Write down what you notice! Scientists always write down what they see. Have fun! Then share what you found with a friend or a grown-up.
Do this with a grown-up139. Why Do 3D Printers Print in Layers?
Stack coin-thin clay pancakes into a tiny cup, on a table with a grown-up. Could you make an arch without supports? What did each layer add? Write down what you notice! Scientists always write down what they see. Have fun!
Do this with a grown-up140. Why Do Welders Wear a Dark Mask?
Compare looking at a lamp through clear plastic, and through dark sunglasses. And never look at the sun! Which view is gentler? What job did the dark filter do? Write down what you notice! Scientists always write down what they see. Have fun!
Do this with a grown-up141. Why Does a Potter's Wheel Spin?
Spin a blob of play dough on a lazy Susan, and press gently, on a table with a grown-up. Did the blob stay rounder than when you squeezed it still? What did the spin add? Write down what you notice! Scientists always write down what they see. Have fun! Then share what you found with a friend or a grown-up.
Do this with a grown-up142. Why Do Carpenters Use Squares?
Trace a book corner, and then a cereal-box corner, and test both with a square, with a grown-up. Which corner is closer to 90 degrees? What would a tilted wall do to a door? Write down what you notice! Scientists always write down what they see. Have fun! Then share what you found with a friend or a grown-up.
Do this with a grown-up143. Why Does Paint Dry?
Paint two paper scraps, and leave one in still air and one near a fan, with a grown-up nearby. Which film sets first? What did the moving air steal? Write down what you notice! Scientists always write down what they see. Have fun! Then share what you found with a friend or a grown-up.
Do this with a grown-up144. Why Do Zippers Zip?
Look closely at an open jacket zipper, with a grown-up. Are the teeth hooks or bumps? What job does the slider's Y shape do? Write down what you notice! Scientists always write down what they see. Have fun!
Do this with a grown-up145. Why Does a Vacuum Cleaner Suck?
Hold a light tissue near the intake side of a running fan, with a grown-up. Keep fingers clear! Does the tissue drift in? What moved the tissue, the air, or the fan? Write down what you notice! Scientists always write down what they see. Have fun! Then share what you found with a friend or a grown-up.
Do this with a grown-up146. Why Do Firefighters Use Axes and Hoses?
With a grown-up, blow out a birthday candle, and then cover a second candle with a cup. Which move stole heat? Which one stole air? How is a hose more like one of those moves? Scientists always write down what they see. Have fun!
Do this with a grown-up147. Why Do Doctors Wear Gloves?
In the kitchen with a grown-up, spread a little flour on one hand, then put on a glove and touch a dark plate. Did flour reach the plate? What did the glove stop? Write down what you notice! Scientists always write down what they see. Have fun!
Do this with a grown-up148. Why Does a Cash Register Beep?
Listen to a microwave finish, and a smoke alarm. Just talk about it, and don't test alarms! Which beep means done, and which means help? Why would a store want the gentle kind? Write down what you think! Scientists always write down what they see. Have fun! Then share what you found with a friend or a grown-up.
Do this with a grown-up149. Why Do Libraries Use the Same Number Codes?
Pick two books at home, and invent a two-digit code for each topic, with a grown-up. Would a visitor find them? What makes a shared code more useful than a secret one? Write down your answers! Scientists always write down what they see. Have fun!
Do this with a grown-up150. Why Do Makers Prototype First?
Build two paper-cup phones with different string lengths, with a grown-up to help. Which whispered word traveled better? What did the first try teach the second try? Write down what you learn! Scientists always write down what they see. Have fun! Then share what you found with a friend or a grown-up.
Do this with a grown-up