When you think about what life will be like 50 years from now, what comes to mind? Will we have flying cars? Will there be a colony of Earthlings on Mars? Will robots have taken over the world?

Millions of robots already exist, but it's highly unlikely that they'll rise up and band together to take over Earth.

What comes to mind when you envision a robot? Do you think of machines designed to act and look like human beings? These robots, called androids, still mainly exist only in science fiction movies.

Most robots are far simpler and much more practical. Some examples include vending machines, robotic arms used in factories, remote control toys, and automatic teller machines (ATMs). Of course, there are also highly-specialized, complex robots, such as the Mars exploration rovers launched by NASA.

Like defining "art," it can be hard to define exactly what a robot is. Some scientists define robots as mechanical devices capable of performing particular tasks on command or according to programmed instructions.

Robots are extremely useful, because they can do things that are too difficult, dangerous, or repetitive for humans to do efficiently. For example, many assembly line tasks in factories can be done more quickly and accurately by robots than humans. Likewise, the Mars exploration rovers can explore Mars when it would be too dangerous for humans to do so.

When thinking about building a robot, it's important to keep in mind the four essential characteristics that help to define a robot. These characteristics include sensing, movement, energy, and intelligence.

Robots must be able to sense their surroundings. Rather than eyes, ears, noses, and hands, robots can be built with sensors that detect things such as light, pressure, chemicals, and sound.

Robots must also be able to move. Movement can be accomplished via wheels, legs, thrusters, or all sorts of other mechanisms. Movement is linked to the need for energy. Robots usually contain a power source, such as a battery or a solar panel.

Finally, robots must have some kind of intelligence. This usually takes the form of some way of programming the robot with instructions.

While it might seem like a tall order to create a robot with sensors, movement, a power source, and programming, it can actually be quite simple and affordable. Scientists and teachers have developed a wide range of tools, supplies, and instructions to help budding engineers explore the world of electronics and robotics design.

Check out the Try It Out section below to discover some examples of basic, affordable robot-building activities. If you want hands-on experience building a robot, all you need is a little bit of desire, a whole lot of imagination, a few tools and supplies, and some help and guidance from an adult family member or friend.

So what are you waiting for? Get building! The world needs more robots and more people to build them. Maybe you'll be the person to develop the next groundbreaking robot that will quickly and accurately do homework! OK, maybe that's a bit ambitious, but we bet your imagination can come up with something that'll be really cool and fun to build!

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