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A Million Whys Book 15: The Robot Expedition

All 150 questions from Book 15, each with a short video answer. Tap any video to watch.

Videos150 videos
Why Do We Call a Machine a Robot?

Why Do We Call a Machine a Robot?

Question 1

We call a machine a robot when it can sense, decide, and act! Sensors notice the world around it. Its computer brain follows a program to choose what to do.

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Why Isn't a Remote-Control Car a Robot?

Why Isn't a Remote-Control Car a Robot?

Question 2

A remote-control car is not a robot because you do the thinking! You watch where it goes, and you choose every turn. The car just obeys, while a robot does some sensing and deciding by itself.

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Why Is a Toaster Not a Robot but a Robot Vacuum Is?

Why Is a Toaster Not a Robot but a Robot Vacuum Is?

Question 3

A toaster does the same thing no matter what, but a robot vacuum looks around and chooses! A toaster follows a timer or a heat setting. A vacuum senses and decides, and that is what makes it a robot.

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Where Does the Word Robot Come From?

Where Does the Word Robot Come From?

Question 4

The word robot comes from a Czech word, robota, which means hard work! A writer named Karel Čapek used it in a play in 1920. The word was invented before real robots existed, so stories came first and machines came later!

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Why Do Many Robots Look Nothing Like People?

Why Do Many Robots Look Nothing Like People?

Question 5

Robots are built to do a job, so their shapes copy their jobs! A floor cleaner is flat and round, a factory robot is an arm that reaches, and a rover has wheels. Engineers call this form follows function.

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Why Do Engineers Sometimes Build Robots in Human Shapes?

Why Do Engineers Sometimes Build Robots in Human Shapes?

Question 6

Engineers sometimes build human-shaped robots because the world is built for people! Stairs, doors, tools, and handles are made for human bodies. A robot shaped like us can use them without changing anything.

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Why Does Every Robot Need a Body, a Brain, and a Power Source?

Why Does Every Robot Need a Body, a Brain, and a Power Source?

Question 7

Every robot needs a body, a brain, and a power source! The body moves and does the work, the brain makes the choices, and the power gives energy to everything. Take away any one of them, and the robot cannot work.

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How Does a Robot Get the Energy to Move?

How Does a Robot Get the Energy to Move?

Question 8

Most robots get their energy from batteries! A battery stores energy that can turn into electricity. That electricity runs the motors and the computer, so the robot can move, sense, and think.

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What Does a Robot's Brain Actually Do?

What Does a Robot's Brain Actually Do?

Question 9

A robot's brain is a small computer that follows a program! It reads numbers from the sensors and decides what to tell the motors. It does not think like a person does.

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Why Do Robots Keep Repeating Sense, Think, Act?

Why Do Robots Keep Repeating Sense, Think, Act?

Question 10

Robots keep repeating sense, think, act, because the world keeps changing! After each action, the robot senses again to see what changed. That loop lets it fix mistakes and handle surprises.

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Why Can a Robot Do the Same Job Thousands of Times Without Getting Tired?

Why Can a Robot Do the Same Job Thousands of Times Without Getting Tired?

Question 11

A robot can do the same job thousands of times because motors do not get tired! They do not get sore, bored, or sleepy. Doing one job over and over is where robots are strongest.

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Why Are Some Easy Things for People Really Hard for Robots?

Why Are Some Easy Things for People Really Hard for Robots?

Question 12

Some easy things for people are really hard for robots! Picking up an egg uses lots of senses and tiny adjustments that your brain does without thinking. A robot has to be told every part.

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Why Does a Robot's Weight Matter So Much to Designers?

Why Does a Robot's Weight Matter So Much to Designers?

Question 13

A robot's weight matters because heavy robots need bigger motors, and bigger motors need bigger batteries! And those batteries are heavy too. So designers try to keep robots light but strong.

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Why Isn't a Laptop a Robot?

Why Isn't a Laptop a Robot?

Question 14

A laptop is not a robot because it cannot move around or change the physical world on its own! It can sense keys and show results on a screen. But a robot has a body that moves parts in the real world.

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Why Was the First Factory Robot Just an Arm?

Why Was the First Factory Robot Just an Arm?

Question 15

The first factory robot was just an arm because an arm could do a useful job right away! It was called Unimate, and it started work in 1961. It lifted hot, heavy metal parts, which was risky for people.

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Why Aren't Real Robots as Clever as Robots in Movies?

Why Aren't Real Robots as Clever as Robots in Movies?

Question 16

Real robots are not as clever as movie robots, because movies are made for fun! Movie robots talk, walk, and understand everything. Real robots usually do one kind of job and need clear instructions from people.

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Why Do Engineers Draw a Robot Before They Build It?

Why Do Engineers Draw a Robot Before They Build It?

Question 17

Engineers draw a robot before building it, because drawing is cheaper and faster! Changing a drawing takes seconds, with just an eraser. Changing a finished robot can take days, and sometimes weeks.

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Why Do Engineers Test a Robot Again and Again?

Why Do Engineers Test a Robot Again and Again?

Question 18

Engineers test a robot again and again, because problems often show up only some of the time! A wheel might slip on a shiny floor, or a sensor might fail in sunlight. Testing finds these problems before the robot starts its real job.

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Why Do Robots Have Emergency Stop Buttons?

Why Do Robots Have Emergency Stop Buttons?

Question 19

Robots have emergency stop buttons so anyone can stop them fast if something goes wrong! The button is called an e-stop, short for emergency stop. It cuts power so the robot stops quickly.

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Why Are Some Big Robots Kept Behind Safety Fences?

Why Are Some Big Robots Kept Behind Safety Fences?

Question 20

Big factory robots are kept behind safety fences because their arms swing fast and with strong force! The fence keeps people at a safe distance while the robot works. A robot does not know a person is in the way unless it is built to notice.

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Why Can Some Robots Work Safely Next to People?

Why Can Some Robots Work Safely Next to People?

Question 21

Some robots can work safely next to people because they are designed to share space! They are called collaborative robots, or cobots. Careful design makes sharing possible, and it is what sets cobots apart.

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What Does It Mean When a Robot Is Autonomous?

What Does It Mean When a Robot Is Autonomous?

Question 22

An autonomous robot makes its own decisions about how to do its job! Autonomous means able to run by itself. It uses its sensors and its program, and it does not need someone to steer it.

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Why Do Some Robots Need a Person to Steer Them From Far Away?

Why Do Some Robots Need a Person to Steer Them From Far Away?

Question 23

Some robots are steered by a person far away, because some jobs are too tricky or risky for a program alone! This is called teleoperation, which means working from a distance. A person can use judgment when something unexpected happens.

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Why Do Engineers Send Robots to Places That Are Too Hot, Too Deep, or Too Far for People?

Why Do Engineers Send Robots to Places That Are Too Hot, Too Deep, or Too Far for People?

Question 24

Engineers send robots to places that are too hot, too deep, or too far for people! Robots do not need air, food, or comfortable temperatures. They can go first, so people can learn about a place before they go.

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How Small Can a Robot Get, and How Big?

How Small Can a Robot Get, and How Big?

Question 25

Robots can be super tiny or really huge, and size depends on the job! Scientists have built flying robots smaller than a coin. Others are smaller than a grain of rice, and some are as big as a house.

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What Is a Sensor, and Why Do Robots Need Them?

What Is a Sensor, and Why Do Robots Need Them?

Question 26

A sensor is a part that measures something in the world and turns it into a signal! That signal is usually a number that the robot's brain can use. Without sensors, a robot would be blind and numb.

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How Does a Bump Sensor Tell a Robot It Has Hit a Wall?

How Does a Bump Sensor Tell a Robot It Has Hit a Wall?

Question 27

A bump sensor tells a robot it hit a wall by closing a tiny switch! When the robot bumps something, the switch is pushed. Then electricity can flow, and the brain gets a signal.

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How Does a Robot’s Ultrasonic Sensor Find How Far Away a Wall Is?

How Does a Robot’s Ultrasonic Sensor Find How Far Away a Wall Is?

Question 28

An ultrasonic sensor finds how far away a wall is by sending out sound and listening for the echo! The sound is too high-pitched for us to hear. The longer the echo takes, the farther away the wall is.

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How Does a Robot Use a Laser Beam to Map the Space Around It?

How Does a Robot Use a Laser Beam to Map the Space Around It?

Question 29

A lidar sensor uses laser light to map the space around a robot! It spins around and sends out thousands of short, safe laser pulses every second. Each pulse is timed as it bounces back.

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Why Can a Robot Follow a Black Line on the Floor?

Why Can a Robot Follow a Black Line on the Floor?

Question 30

A robot can follow a black line because black soaks up light and white bounces it back! A sensor underneath shines a little light on the floor. It measures how much light comes back.

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How Does a Robot Know Which Way Is Up?

How Does a Robot Know Which Way Is Up?

Question 31

A robot knows which way is up with two tiny parts, an accelerometer and a gyroscope! One feels the pull of gravity, and the other feels turning. Together they tell the robot how it is tilted.

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How Does a Robot Know How Far It Has Driven?

How Does a Robot Know How Far It Has Driven?

Question 32

A robot knows how far it has driven by counting how much its wheels turn! A part called an encoder counts the turns. Then it multiplies the turns by the distance around the wheel.

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Why Do Some Robots Have Touch-Sensitive Skin?

Why Do Some Robots Have Touch-Sensitive Skin?

Question 33

Some robots have touch-sensitive skin so they know where they are touched and how hard! The skin is a layer with many tiny pressure sensors. It helps robots be gentle and safe, just like your skin helps you.

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How Can a Robot Use a Camera to Find a Ball?

How Can a Robot Use a Camera to Find a Ball?

Question 34

A robot can use a camera to find a ball by looking for patches of the ball's color! A camera takes a picture made of many tiny dots called pixels. Each pixel is stored as a number for its color.

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Why Do Robots Sometimes Get Confused by Bright Sunlight?

Why Do Robots Sometimes Get Confused by Bright Sunlight?

Question 35

Robots can get confused by bright sunlight because many robot sensors measure light! Very bright sunlight can overload them, like a flash in your face. Then the sensor cannot tell shadows from objects.

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Why Do Robots Use Many Sensors Instead of Just One?

Why Do Robots Use Many Sensors Instead of Just One?

Question 36

Robots use many sensors because every sensor has weak spots! By combining several sensors, the robot can check one against another. That makes its picture of the world more reliable.

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How Does a Robot Sense Heat?

How Does a Robot Sense Heat?

Question 37

A robot can sense heat in two main ways! Some sensors change how easily electricity flows when they warm up. Others catch infrared light, which warm things give off.

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Why Can a Robot Turn Toward a Clap?

Why Can a Robot Turn Toward a Clap?

Question 38

A robot can turn toward a clap because it uses two or more microphones! The sound reaches the closer microphone a tiny bit sooner. It is also a bit louder there.

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Why Does a Robot with a Light Sensor Follow a Flashlight?

Why Does a Robot with a Light Sensor Follow a Flashlight?

Question 39

A robot with light sensors follows a flashlight by comparing left and right! It has one sensor on the left and one on the right. A simple rule makes it look like it is chasing the light.

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Why Do Robots Use GPS Outdoors but Not Inside?

Why Do Robots Use GPS Outdoors but Not Inside?

Question 40

Robots use GPS outdoors because it listens to signals from satellites high above Earth! The signals are very weak, since they travel a long way. Walls and roofs block or weaken them, so GPS struggles inside.

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Why Doesn't a Robot Vacuum Fall Down the Stairs?

Why Doesn't a Robot Vacuum Fall Down the Stairs?

Question 41

A robot vacuum does not fall down the stairs because it has cliff sensors! They shine infrared light at the floor and check for the light that bounces back. At a stair edge, almost no light returns, so the robot knows to stop.

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Why Do Robot Sensors Sometimes Get Things Wrong?

Why Do Robot Sensors Sometimes Get Things Wrong?

Question 42

Robot sensors sometimes get things wrong because the real world is messy! Dust, glare, noise, and shiny, clear, or soft surfaces can fool them. Even the best sensors are never perfect.

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Why Do Automatic Doors Open as You Walk Up?

Why Do Automatic Doors Open as You Walk Up?

Question 43

Automatic doors open as you walk up because a sensor notices you! It sits above the door and watches the space in front. When something moves in, it tells the motor to open.

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How Does a Robot Arm Know When It Has Reached the End of Its Swing?

How Does a Robot Arm Know When It Has Reached the End of Its Swing?

Question 44

A robot arm knows where its end is by counting turns in its motor! Some arms also have limit switches at the ends of the swing. Counting and switches work together to keep the arm safe.

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How Can a Magnet Tell a Robot Where Its Parts Are?

How Can a Magnet Tell a Robot Where Its Parts Are?

Question 45

A magnet can tell a robot where its parts are, with a sensor that feels magnetism! The sensor is called a Hall sensor. A small magnet goes on the moving part, and the sensor stays still.

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How Does a Robot Hand Know How Hard to Squeeze?

How Does a Robot Hand Know How Hard to Squeeze?

Question 46

A robot hand knows how hard to squeeze by using feedback! Some fingers have pressure sensors, and the motor reports how hard it is working. The brain stops closing when it reaches a set limit.

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How Does a Light Curtain Stop a Factory Robot When Someone Gets Close?

How Does a Light Curtain Stop a Factory Robot When Someone Gets Close?

Question 47

A light curtain stops a factory robot by using a row of invisible light beams! A sensor on the other side checks that each beam arrives. If a hand breaks a beam, the robot is told to stop.

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How Can a Robot Sort Red Blocks From Blue Ones?

How Can a Robot Sort Red Blocks From Blue Ones?

Question 48

A robot can sort red blocks from blue ones by measuring the color of light that comes back! A color sensor or a camera does the measuring. Then a program compares the numbers with simple rules.

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Why Do Some Robots Carry Gas Sensors?

Why Do Some Robots Carry Gas Sensors?

Question 49

Some robots carry gas sensors because they can notice air that is unsafe for people! A gas sensor reacts to certain gases, like smoke or harmful fumes. It can notice things our noses may not.

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How Does a Robot Find Its Charging Station?

How Does a Robot Find Its Charging Station?

Question 50

A robot vacuum finds its charging station by following a signal from the dock! The dock sends out an invisible beam of infrared light. When the battery is low, the robot looks for it and drives toward it.

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Why Does a Motor Spin When You Connect a Battery?

Why Does a Motor Spin When You Connect a Battery?

Question 51

A motor spins because electricity can turn a coil of wire into a magnet! Other magnets nearby push and pull on it, and that makes the coil turn. Almost every robot uses electric motors to move.

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Why Do Robot Motors Have Tiny Gearboxes?

Why Do Robot Motors Have Tiny Gearboxes?

Question 52

A small motor spins very fast, but it has very little turning power! A tiny gearbox trades speed for strength. That is how a small motor can help a robot lift something heavy.

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What Is a Servo Motor?

What Is a Servo Motor?

Question 53

A servo motor is a motor with its own helper brain! You tell it an angle, and it turns there and holds still. Servos move robot arms and legs to exact angles.

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Why Can a Stepper Motor Move in Tiny, Exact Steps?

Why Can a Stepper Motor Move in Tiny, Exact Steps?

Question 54

A stepper motor turns in tiny, exact steps! Each electrical pulse turns it by one small step, like 1.8 degrees. Because the steps are exact, a robot can simply count them. 3D printers use stepper motors.

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Why Do Robots Use Wheels More Often than Legs?

Why Do Robots Use Wheels More Often than Legs?

Question 55

Wheels are simple, quick, and save energy on flat ground! Legs are more complicated, but they can step over rocks and climb stairs. The best choice depends on where the robot will work.

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Why Do Many Walking Robots Have Four Legs?

Why Do Many Walking Robots Have Four Legs?

Question 56

Four legs make a robot steady, because three feet can stay on the ground while one steps! Two-legged walking is much harder to balance. Four legs also spread out the weight and can carry more.

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Why Is Balancing on Two Legs Such a Challenge for a Robot?

Why Is Balancing on Two Legs Such a Challenge for a Robot?

Question 57

Balancing on two legs is hard because the robot's weight must stay over a tiny spot! That spot is where its feet touch the ground. If the weight drifts outside it, the robot tips over.

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How Does a Robot Turn by Spinning Its Wheels at Different Speeds?

How Does a Robot Turn by Spinning Its Wheels at Different Speeds?

Question 58

A two-wheeled robot turns by spinning its wheels at different speeds! No steering wheel is needed. The faster side pushes the robot around toward the slower side.

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Why Do Some Robots Have Tank Treads?

Why Do Some Robots Have Tank Treads?

Question 59

Tank treads are belts that go around the wheels! They spread the robot's weight over a large area, so it does not sink into soft ground. They also grip rough ground.

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Why Do Some Robots Roll on Balls or Special Sideways Wheels?

Why Do Some Robots Roll on Balls or Special Sideways Wheels?

Question 60

Some robots can move sideways without turning, thanks to special wheels! Others balance and roll on a ball. These designs help in tight spaces, like warehouses.

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Why Do Robot Arms Have Joints Like a Shoulder and an Elbow?

Why Do Robot Arms Have Joints Like a Shoulder and an Elbow?

Question 61

Joints let parts of a robot arm bend and turn, just like your shoulder, elbow, and wrist! Each joint adds one more way for the arm to move. More joints reach more places.

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Why Does a Robot Arm Need About Six Joints to Reach Anywhere?

Why Does a Robot Arm Need About Six Joints to Reach Anywhere?

Question 62

To put a robot hand in any spot, at any angle, an arm needs about six joints! Three joints set the position, and three more set the direction. Engineers call this six degrees of freedom.

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How Does a Robot Gripper Pick Up Things?

How Does a Robot Gripper Pick Up Things?

Question 63

A robot gripper is like a hand with two or three fingers that close together! A motor pulls the fingers closed, and rubber pads help them grip. Different jobs use different grippers.

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Why Do Some Robot Hands Use Suction Cups?

Why Do Some Robot Hands Use Suction Cups?

Question 64

A suction cup holds on because air outside pushes it against the surface! A robot pump pulls the air out of the cup. Then the air around us does the holding.

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Why Are Some Robots Soft and Squishy?

Why Are Some Robots Soft and Squishy?

Question 65

A soft robot is made of bendy material, like silicone rubber! Air or liquid fills little hollow chambers and makes the fingers curl. Being soft makes them gentle with delicate things.

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Why Does a Long Robot Arm Lift Less than a Short One?

Why Does a Long Robot Arm Lift Less than a Short One?

Question 66

A long robot arm lifts less because it acts like a lever! The farther a weight is from the shoulder, the more twisting force the motor must make to hold it up. A short arm needs much less.

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Why Do Robots Use Belts and Pulleys?

Why Do Robots Use Belts and Pulleys?

Question 67

A belt and pulleys pass turning from one wheel to another! Unlike gears, they can connect parts that are far apart. They are light, quiet, and a bit flexible.

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Why Do Robot Motors Get Warm?

Why Do Robot Motors Get Warm?

Question 68

Robot motors get warm because some electricity turns into heat! Wires push back on the electricity, and moving parts rub together. A warm motor means a hard-working motor.

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How Does a Robot Arm Know Exactly Where Its Hand Is?

How Does a Robot Arm Know Exactly Where Its Hand Is?

Question 69

A robot arm knows where its hand is by measuring every joint angle! Then it adds up those angles and the arm lengths, using some math. It does not even need a camera.

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Why Does a Robot Sometimes Overshoot Its Stop and Wobble Back?

Why Does a Robot Sometimes Overshoot Its Stop and Wobble Back?

Question 70

A robot overshoots because moving things keep moving! This is called inertia. The robot slides past its target, notices, and wiggles back.

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How Can a Robot Jump or Hop?

How Can a Robot Jump or Hop?

Question 71

A jumping robot stores energy in a spring, then lets it go all at once! A motor squeezes the spring slowly, and a latch releases it in an instant. The robot springs into the air.

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Why Do Some Robots Wriggle Like Snakes?

Why Do Some Robots Wriggle Like Snakes?

Question 72

Snake robots wriggle because they bend in a wave that travels down their body! The wave pushes against the ground or walls and moves them forward. Their long, thin bodies fit where wheels and legs cannot.

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How Can a Robot Balance on Just Two Wheels?

How Can a Robot Balance on Just Two Wheels?

Question 73

A two-wheeled robot balances like a broom on your hand! When it starts to tip, its wheels roll under it to catch it. It looks calm, but it is always catching itself.

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Why Do Some Strong Robots Push with Air or Liquid?

Why Do Some Strong Robots Push with Air or Liquid?

Question 74

Some strong robots use air or liquid under pressure to push a piston! Air makes quick, springy moves, and liquid makes strong, steady ones. These are great when a job needs a lot of force.

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Why Do Robot Builders Choose Lightweight Materials?

Why Do Robot Builders Choose Lightweight Materials?

Question 75

Builders choose lightweight materials because heavy parts take more energy to move and stop! A lighter robot needs smaller motors and batteries. And it can work longer.

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How Does a Robot Vacuum Map a Room?

How Does a Robot Vacuum Map a Room?

Question 76

A robot vacuum draws a map of your room as it drives around! It measures distances to walls and furniture, and counts its wheel turns. Then it cleans the floor in neat lines.

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Why Do Robot Vacuums Get Stuck on Socks and Cords?

Why Do Robot Vacuums Get Stuck on Socks and Cords?

Question 77

A robot vacuum sees the room as a thin flat layer of obstacles at one height! A thin cord or a flat sock may be too low or too thin to notice. Then it drives over them and gets tangled.

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Why Does a Robot Lawn Mower Stay Inside the Yard?

Why Does a Robot Lawn Mower Stay Inside the Yard?

Question 78

A robot lawn mower stays in the yard by sensing an invisible boundary! Usually a thin wire is buried at the edge of the lawn. The wire carries a weak signal that the mower can feel.

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How Do Pool-Cleaning Robots Clean Underwater?

How Do Pool-Cleaning Robots Clean Underwater?

Question 79

A pool robot cleans by pulling water through a filter bag as it drives! It scrubs with brushes and its filter catches the dirt. It follows a pattern across the floor and the walls.

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How Do Window-Cleaning Robots Stick to Glass?

How Do Window-Cleaning Robots Stick to Glass?

Question 80

A window-cleaning robot sticks to glass using suction! A fan or pump pulls air out from under it. Then the air outside pushes the robot against the window.

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Why Do Warehouses Use Flat Robots That Carry Shelves?

Why Do Warehouses Use Flat Robots That Carry Shelves?

Question 81

In some warehouses, flat robots slide under a tall shelf, lift it, and carry it to a worker! The shelves come to the people, instead of people walking the aisles. That saves time and steps.

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How Do Factory Robots Paint Cars So Evenly?

How Do Factory Robots Paint Cars So Evenly?

Question 82

A painting robot repeats the exact same path, at the same speed, every time! That gives each part of the car the same amount of paint. The paint lands in a smooth, even layer.

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How Can a Robot Pick a Strawberry Without Squishing It?

How Can a Robot Pick a Strawberry Without Squishing It?

Question 83

A strawberry-picking robot finds ripe berries by color, then picks them gently! A camera spots the red berries. A soft gripper or small cutter reaches the stem, so the berry isn't squeezed.

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Why Do Farm Robots Drive Along the Crop Rows?

Why Do Farm Robots Drive Along the Crop Rows?

Question 84

Farm robots drive along crop rows to avoid stepping on the plants! They use GPS and cameras to follow very straight lines. Staying in the lines protects the crops.

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How Do Robots Sort Recycling?

How Do Robots Sort Recycling?

Question 85

Robots sort recycling by looking at each item as it rides past on a conveyor belt! Cameras and sensors tell the items apart. A robot arm or a puff of air puts each one in the right bin.

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What Is Canadarm2, and What Does It Do?

What Is Canadarm2, and What Does It Do?

Question 86

Canadarm2 is a huge robotic arm on the International Space Station, built in Canada! It is about 17.6 meters long, and it has seven joints. Astronauts use it to catch spacecraft and move equipment.

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How Do Small Robots Crawl Through Pipes to Find Leaks?

How Do Small Robots Crawl Through Pipes to Find Leaks?

Question 87

Pipe robots are small rolling machines with a camera and a light! They travel through pipes to look for cracks, blockages, and leaks. They send pictures back to a person, so no one has to dig up the street.

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Why Do Robots Climb Wind Turbines and Tall Towers?

Why Do Robots Climb Wind Turbines and Tall Towers?

Question 88

Robots climb wind turbines and towers to check them for cracks and damage! The blades are very tall, so checking them is hard work. Robots mean fewer risky climbs for people.

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Why Do Delivery Robots Roll Along Sidewalks?

Why Do Delivery Robots Roll Along Sidewalks?

Question 89

Delivery robots are small, wheeled boxes that roll along sidewalks at walking speed! They use cameras, lidar, and GPS to follow a route. They are designed to be slow and careful.

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How Can Small Robots Help Search a Collapsed Building?

How Can Small Robots Help Search a Collapsed Building?

Question 90

Small, bendy robots can crawl into narrow gaps after a building has fallen down! They carry cameras, lights, and microphones. They help rescue teams see where it is safe to dig.

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How Do Robots Scrub the Bottoms of Big Ships?

How Do Robots Scrub the Bottoms of Big Ships?

Question 91

Robots scrub ship bottoms to remove tiny sea animals like barnacles! A clean hull glides through the water more smoothly. That saves fuel and protects the sea.

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How Can a Robot Build a Brick Wall?

How Can a Robot Build a Brick Wall?

Question 92

A brick-laying robot has a long arm that picks up a brick, adds glue, and sets it in an exact spot! It follows a plan that says where every brick goes. It can lay a brick every few seconds.

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Why Do Robots in Science Labs Move Tiny Drops of Liquid?

Why Do Robots in Science Labs Move Tiny Drops of Liquid?

Question 93

Lab robots move tiny drops of liquid because they can measure more exactly than hands! They use thin tubes to move the drops from one container to another. A drop can be smaller than a raindrop.

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Why Do Greenhouse Robots Check Plants One by One?

Why Do Greenhouse Robots Check Plants One by One?

Question 94

Greenhouse robots check plants one by one so they can spot problems early! They roll or hang between the rows and use cameras to look at each plant. A small problem is easier to fix early, before it spreads.

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Why Can Some Robots Work in Total Darkness?

Why Can Some Robots Work in Total Darkness?

Question 95

Some robots can work in total darkness because they make their own signals! They send out light, sound, or radio waves, and read the echoes. Touch sensors work in the dark, too.

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How Do Warehouse Robots Avoid Bumping Into Each Other?

How Do Warehouse Robots Avoid Bumping Into Each Other?

Question 96

Warehouse robots avoid bumping by following traffic rules, like cars do! A central computer acts like a traffic controller and gives each robot a path. Each robot also has its own sensors.

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How Do Robots Pack Cookies Without Breaking Them?

How Do Robots Pack Cookies Without Breaking Them?

Question 97

A cookie-packing robot handles each cookie slowly and softly! A camera spots where each cookie is. A soft gripper or a gentle suction pad picks it up without pressing too hard.

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Why Do Robots Clean Solar Panels?

Why Do Robots Clean Solar Panels?

Question 98

Dust and dirt on a solar panel block some sunlight, so the panel makes less electricity! Cleaning robots wipe the panels so more light gets through. More sunlight means more power.

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How Do Robots Sort Parcels So Fast?

How Do Robots Sort Parcels So Fast?

Question 99

Robots sort parcels fast by reading a label on each one as it rides a belt! A computer decides which bin each parcel belongs in. Then a small arm, pusher, or tilting tray sends it that way.

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Why Can't One Robot Cook, Clean, and Fold Laundry Yet?

Why Can't One Robot Cook, Clean, and Fold Laundry Yet?

Question 100

One robot can't cook, clean, and fold laundry yet because each job is very different! Each needs different tools, senses, and skills. Specialist robots are easier to make than all-rounders.

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Why Do Most Small Drones Have Four Rotors?

Why Do Most Small Drones Have Four Rotors?

Question 101

Most small drones have four rotors because four gives a great mix of balance and control! Each rotor pushes air downward to hold the drone up. Speeding up some rotors and slowing others lets the drone tilt, turn, and move.

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How Does a Drone Stay Level in the Air?

How Does a Drone Stay Level in the Air?

Question 102

A drone stays level because it feels every tiny tilt and fixes it, hundreds of times each second! A small sensor notices if one side dips. A tiny computer then adjusts the motors to level it out again.

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Why Do Two of a Drone's Propellers Spin One Way and Two the Other?

Why Do Two of a Drone's Propellers Spin One Way and Two the Other?

Question 103

Two propellers spin one way and two spin the other so the drone stays pointing straight! Every spinning propeller gives the drone body a small twist in the opposite direction. Spinning in pairs makes those twists cancel out.

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Why Does a Drone Tilt to Fly Forward?

Why Does a Drone Tilt to Fly Forward?

Question 104

A drone tilts to fly forward because a tilt turns its up-and-down push into a forward push! The rotors push air backward as well as down. Pushing air back moves the drone forward.

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Why Can't Most Drones Fly for Very Long?

Why Can't Most Drones Fly for Very Long?

Question 105

Most drones can't fly for very long because holding themselves up takes a lot of power! A drone must push air downward all the time, or it falls. Most small drones fly for about 20 to 30 minutes before the battery runs low.

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Why Do Some Drones Have Little Cages Around the Propellers?

Why Do Some Drones Have Little Cages Around the Propellers?

Question 106

Some drones have little cages around their propellers to keep the spinning blades and everything nearby safe! If the drone bumps into something, the cage takes the hit. That protects the blades, the walls, and people.

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Why Must Drones Stay Away From Airports and Crowds?

Why Must Drones Stay Away From Airports and Crowds?

Question 107

Drones must stay away from airports and crowds because flying safely means keeping everyone safe! A drone that falls or crashes could hurt someone or damage things. Rules tell pilots where they can and can't fly.

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How Can a Drone Help a Farmer Check a Big Field?

How Can a Drone Help a Farmer Check a Big Field?

Question 108

A drone can help a farmer check a big field by flying over it and taking photos from above! Special cameras can tell healthy plants from stressed ones. Then the farmer knows where to look first.

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How Do Drones Make Maps and 3D Models?

How Do Drones Make Maps and 3D Models?

Question 109

Drones make maps and 3D models by taking hundreds of photos and letting a computer do the math! Each photo is taken from a slightly different place. The differences tell the computer how far away each spot is.

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Why Can Drone Light Shows Paint Pictures in the Night Sky?

Why Can Drone Light Shows Paint Pictures in the Night Sky?

Question 110

Drone light shows paint pictures in the night sky because each drone is a flying dot of light! A computer plans where every drone should be at every moment. Together, hundreds of lights make a picture.

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How Do Delivery Drones Carry Packages?

How Do Delivery Drones Carry Packages?

Question 111

Delivery drones carry packages on a hook or in a small box and set them down gently at the spot! They fly high to stay clear of trees and buildings. Because of the battery, they carry only light things on short trips.

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How Do Scientists Use Drones to Study Tall Trees and Forest Canopies?

How Do Scientists Use Drones to Study Tall Trees and Forest Canopies?

Question 112

Scientists use small drones to study tall trees because drones can fly right up to the treetops! Tree canopies are full of leaves, branches, and animals, high above the ground. They are very hard to study from below.

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Why Can a Drone Hover but an Airplane Can't?

Why Can a Drone Hover but an Airplane Can't?

Question 113

A drone can hover because its propellers are tiny spinning wings, but an airplane's wings must keep moving forward! Wings make lift only when air flows past them. A drone's spinning blades make air flow even when the drone stays still.

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Why Is a Rover Not Just a Small Car?

Why Is a Rover Not Just a Small Car?

Question 114

A rover is not just a small car because it must drive itself in places where nobody can fix it! It has strong wheels, cameras, tools, and its own power. It is more like a robot scientist on wheels.

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How Does a Rover Keep Its Wheels on the Ground Over Bumpy Rocks?

How Does a Rover Keep Its Wheels on the Ground Over Bumpy Rocks?

Question 115

Many rovers keep their wheels on bumpy rocks with a clever suspension called a rocker-bogie! Each side has wheels joined by pivoting arms. When one wheel goes up, the arms tilt so the other wheels stay down.

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Why Does a Rover Only Drive a Little Bit at a Time?

Why Does a Rover Only Drive a Little Bit at a Time?

Question 116

A rover drives only a little bit at a time because messages from Earth take minutes to arrive! So engineers can't steer it live, like a toy car. Instead, they send a plan and the rover carries it out slowly and carefully.

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Why Do Rovers Carry Rock-Zapping Lasers and Drills?

Why Do Rovers Carry Rock-Zapping Lasers and Drills?

Question 117

Rovers carry rock-zapping lasers and drills to find out what rocks are made of! A laser zaps a rock and makes a tiny puff of glowing gas. Drills collect samples from inside the rock.

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How Do Rovers Get Power on Other Worlds?

How Do Rovers Get Power on Other Worlds?

Question 118

Rovers get power on other worlds from solar panels or from a special long-lasting battery! The choice depends on where the rover is going. Sunlight can be weak, dusty, or missing for long nights.

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Why Do Rovers Have Cameras on Tall Masts?

Why Do Rovers Have Cameras on Tall Masts?

Question 119

Rovers have cameras on tall masts so they can see farther, like standing on tiptoe! Height lets a camera look over rocks and bumps, so it can see what lies ahead. That helps the team plan a safe route.

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Why Do We Send Rovers to the Moon?

Why Do We Send Rovers to the Moon?

Question 120

We send rovers to the Moon because it is close, so it is a great place to test machines! Rovers can study rocks, dust, and even search for ice. What we learn helps us prepare for farther places.

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How Do Underwater Robots Take Pictures in the Dark Deep?

How Do Underwater Robots Take Pictures in the Dark Deep?

Question 121

Underwater robots take pictures in the dark deep by bringing their own bright lights! Sunlight does not reach the deep ocean. Robots also use sound to sense the seafloor.

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Why Do Some Underwater Robots Glide by Changing Their Weight?

Why Do Some Underwater Robots Glide by Changing Their Weight?

Question 122

Some underwater robots glide by changing their weight, pumping oil in and out of a bladder! Making itself lighter or heavier is the whole trick. Wings then turn up-and-down motion into a slow glide forward.

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How Do Robots Explore Caves That Are Too Narrow for People?

How Do Robots Explore Caves That Are Too Narrow for People?

Question 123

Robots explore caves that are too narrow for people because they can be small, bendy, and brave! Caves are narrow, twisty, and have no GPS. Robots go in with cameras and send maps back out.

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Why Do Engineers Copy Animals When They Build Robots?

Why Do Engineers Copy Animals When They Build Robots?

Question 124

Engineers copy animals when they build robots because animals have been solving problems for millions of years! Nature has already tested many good designs. This clever idea is called biomimicry, which means copying life.

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Why Do Swarms of Tiny Robots Work Together Like Ants?

Why Do Swarms of Tiny Robots Work Together Like Ants?

Question 125

Swarms of tiny robots work together like ants because each one follows a few simple rules! Each robot senses only its neighbors. Together, they can do big jobs, like searching a large area.

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How Does a Robot Decide What to Do Next?

How Does a Robot Decide What to Do Next?

Question 126

A robot decides what to do next by following rules that connect what its sensors say to what it should do! The computer checks the rules one at a time. Then it picks an action, and does it all again.

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Why Must Instructions for a Robot Be So Exact?

Why Must Instructions for a Robot Be So Exact?

Question 127

Instructions for a robot must be exact because a computer can't guess what you mean! People fill in missing details without noticing. A robot only does exactly what the instructions say.

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Why Do Robot Instructions Use If-Then Rules?

Why Do Robot Instructions Use If-Then Rules?

Question 128

Robot instructions use if-then rules so a robot can make choices when things change! An if-then rule says: if something is true, then do an action. For example, if the light is red, then stop.

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Why Does a Robot Check, Act, and Check Again?

Why Does a Robot Check, Act, and Check Again?

Question 129

A robot checks, acts, and checks again because the world changes while it works! A wheel might slip, or someone might step in front. Checking after each move lets the robot correct its mistakes.

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Why Can a Robot Get Out of a Maze by Always Turning Left?

Why Can a Robot Get Out of a Maze by Always Turning Left?

Question 130

A robot can get out of a maze by always turning left because it follows one simple wall rule! It keeps one side touching the wall as it moves. That path leads along the walls, all the way to the exit.

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Why Do Robots Need Maps or Landmarks?

Why Do Robots Need Maps or Landmarks?

Question 131

Robots need maps or landmarks because a robot has to know where it is before it can decide where to go! A map shows the places, and landmarks help the robot find its spot on the map. Without them, small errors add up until the robot is lost.

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Why Do Robots Take Tiny Measurements Many Times a Second?

Why Do Robots Take Tiny Measurements Many Times a Second?

Question 132

Robots take tiny measurements many times a second so they can notice and fix small problems right away! If a robot checks only once a second, it could drift far off course. Checking a hundred times a second keeps it steady.

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Why Can a Robot Fail Even When It Follows Every Step Perfectly?

Why Can a Robot Fail Even When It Follows Every Step Perfectly?

Question 133

A robot can fail even when it follows every step perfectly if the world is different from what the steps expected! The instructions were fine, but they did not cover that surprise. Real life is full of surprises.

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How Does a Robot Know When Its Job Is Finished?

How Does a Robot Know When Its Job Is Finished?

Question 134

A robot knows its job is finished when a test in its program becomes true! Sensors check the test again and again. When the answer is yes, the robot stops.

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What Does a Robot Do When Something Blocks Its Path?

What Does a Robot Do When Something Blocks Its Path?

Question 135

When something blocks its path, a robot stops, thinks, and tries a plan B! First, a sensor notices the blockage. Then the robot picks a new route, waits, or asks for help.

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Why Do Some Robots Remember Where They Have Been?

Why Do Some Robots Remember Where They Have Been?

Question 136

Some robots remember where they have been by keeping a record of their path or a map of what they have seen! That helps them avoid going over the same ground again. It also helps them find the way back.

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How Can a Robot Arm Learn by Trying Again and Again?

How Can a Robot Arm Learn by Trying Again and Again?

Question 137

A robot arm can learn by trying again and again, keeping the changes that help! This is called trial and error. After many tries, the arm gets better.

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Why Do Builders Test Robot Ideas with Cardboard First?

Why Do Builders Test Robot Ideas with Cardboard First?

Question 138

Builders test robot ideas with cardboard first because cardboard is cheap and easy to change! A model can be changed in minutes. Mistakes found early are cheap and quick to fix.

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What Happens at a Kids' Robot-Building Contest?

What Happens at a Kids' Robot-Building Contest?

Question 139

At a kids' robot-building contest, teams build robots to meet a challenge and cheer each other on! They test, fix problems, and try again as time runs out. Everyone shares ideas and learns something new, from the youngest to the oldest.

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How Can a Game of Robot Says with a Friend Show How a Robot Reads Steps?

How Can a Game of Robot Says with a Friend Show How a Robot Reads Steps?

Question 140

A game of Robot Says shows how a robot reads steps, because the robot player does exactly what is said! No more and no less. If the steps are clear and in the right order, the robot succeeds.

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How Can You Build a Cardboard Robot Arm That Really Grips?

How Can You Build a Cardboard Robot Arm That Really Grips?

Question 141

You can build a cardboard robot arm that really grips with cardboard strips, paper fasteners, string, and a rubber band! The strips are the arm parts, and the fasteners are the joints. A string closes the gripper, and a rubber band opens it.

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Why Do Robot Builders Wear Safety Glasses?

Why Do Robot Builders Wear Safety Glasses?

Question 142

Robot builders wear safety glasses to protect their eyes while they work! Building uses tools, springs, rubber bands, and small parts. Safety glasses are a quick habit that keeps makers safe.

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Why Do Robot Batteries Need Extra Care?

Why Do Robot Batteries Need Extra Care?

Question 143

Robot batteries need extra care because they store a lot of energy in a small package! Handled properly, they are safe and useful. A grown-up should always be in charge of them.

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How Do the Parts of a Robot Send Messages to Each Other?

How Do the Parts of a Robot Send Messages to Each Other?

Question 144

The parts of a robot send messages to each other as tiny electrical signals along wires! Sensors send information to the brain. The brain sends commands to the motors.

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Why Are the Best Robots Often the Simplest?

Why Are the Best Robots Often the Simplest?

Question 145

The best robots are often the simplest because every extra part is something that could break! A simple robot is cheaper and easier to build. It is also easier to repair.

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Why Do Some Robots Wait for a Signal Before They Start?

Why Do Some Robots Wait for a Signal Before They Start?

Question 146

Many robots wait for a signal before they start so they begin only when everything is ready and safe! The signal can be a button press, a sensor trigger, or a timer. Starting too soon could cause crashes or mistakes.

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Why Do Engineers Try to Build Robots From Parts That Can Be Reused or Recycled?

Why Do Engineers Try to Build Robots From Parts That Can Be Reused or Recycled?

Question 147

Engineers try to build robots from parts that can be reused or recycled because making robots uses energy and materials! Robots are made of metals, plastics, and electronics. Reusing parts keeps those materials in use.

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How Do You Keep a Robot Working for Years?

How Do You Keep a Robot Working for Years?

Question 148

You keep a robot working for years the same way you care for a bike, with regular cleaning, checking, and charging! Dirt blocks sensors, wheels wear out, and batteries lose power over time. A little care goes a long way.

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Why Do Inventors Start with a Problem Before They Design a Robot?

Why Do Inventors Start with a Problem Before They Design a Robot?

Question 149

Inventors start with a problem before they design a robot so the invention is truly useful! First they learn who needs help and what is hard. Then they design a solution.

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What Could Robots Help Scientists Explore Next?

What Could Robots Help Scientists Explore Next?

Question 150

Robots could help scientists explore places that are too dangerous or too far for people! Think of caves on Mars, the deep ocean, or icy moons with hidden oceans. Each trip teaches scientists something new.

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