Track: How Computers Work · Lesson 1 of 10 · Ages: 8+ · Time: 30 minutes
Computers seem like magic. You tap a screen and a game appears. You press a key and a letter shows up. But there is no magic inside, just a handful of parts that each do one job. Today we peek inside, without even opening the box!
Beep says I am a robot, so I have all these parts too. I have a brain that thinks, a place to remember things and a way to see and talk. Beep boop!
What you need
- A pencil and some paper.
- A computer, tablet or phone to look at (you will only look at the outside).
- About half an hour.
Safety first Never open a computer, tablet, phone or game console, and never poke anything into it. Inside there are tiny delicate parts and batteries that can be damaged. We only look at the outside and at drawings today.
A computer is like a kitchen
Imagine a busy kitchen in a restaurant. Each part of the kitchen matches a part of a computer.
| Kitchen | Computer part | Its job |
|---|---|---|
| The chef | Processor (also called the CPU) | Follows the instructions and does the work |
| The counter | Memory (also called RAM) | Holds what you are using right now |
| The fridge and cupboards | Storage | Keeps things safe for a long time |
| The order slips and deliveries | Input devices | Send information in |
| The plate that goes to the table | Output devices | Show you the result |
The chef: the processor
The processor is the part that does the thinking. CPU stands for Central Processing Unit. A recipe is a list of steps, and the chef follows them one by one. A program is the same kind of list: the processor follows its instructions one at a time.
Each step is tiny, such as adding two numbers or comparing them. But a modern processor can do billions of these tiny steps every second. That is how a long list of simple steps turns into a game or a video call.
The counter: memory
A chef cannot cook from the fridge. The chef takes ingredients out and puts them on the counter, where they are easy to reach. That is what memory does. Its full name is RAM, which stands for Random Access Memory. It holds the program and the pictures and numbers the computer is using right now.
The counter has two important facts:
- It is quick to use, but it is small.
- When the computer is switched off, the counter is wiped clean.
Pixel says Ever typed a whole story and forgotten to save it? When the power went off, it was gone. It was only on the counter, not in the fridge. Meow!
The fridge: storage
Storage is where the computer keeps things for later, even when it is switched off. Your photos, games and saved files live here. It is much bigger than memory but a little slower to reach. Computers use different kinds of storage, such as hard drives, solid-state drives and memory cards.
Order slips and plates: input and output
An input device sends information into the computer. A keyboard, a mouse, a microphone, a camera and a touchscreen are all input devices.
An output device sends information out so you can see, hear or feel it. A screen, speakers, headphones and a printer are output devices.
A touchscreen is clever because it does both jobs at once. It takes your touch as input and shows pictures as output.
The whole thing follows a simple pattern: input, process, output. Here is a tiny program that does exactly that:
robot = input("What is your robot called? ")
message = "Hello, " + robot + "!"
print(message)The input line takes information in. The line with message is the processing. The print line is the output.
Did you know? Everything is joined together by the motherboard, the main circuit board. Think of it as the kitchen floor and the doors that let the chef, the counter and the fridge all work together.
Challenges
Try it Walk around your home (no opening anything!). Make a list of five things that have a processor inside. For each one, name an input and an output. Hint: think about a microwave, a TV remote and a music speaker.
Show an example
A microwave has a small processor. Its input is the buttons and the dial. Its outputs are the display, the beep and the light. A TV remote has buttons as input and sends signals to the TV as output.
Try it In the kitchen picture, which part would you swap for a bigger one if your computer felt slow when many programs were open at once?
Show the answer
More memory (RAM), which means a bigger counter. With a bigger counter, the chef can keep more things close at hand without stopping to fetch them.
Grown-ups This lesson needs no equipment. A good extra is to name the parts of a device you own together, using the outside only. If a child is curious about what is inside, a labelled diagram or a library book does the job, and there is no need to take anything apart.
What you learned
- The processor (CPU) follows instructions and does the work.
- Memory (RAM) holds what the computer is using right now and is cleared when the power goes off.
- Storage keeps your files for a long time.
- Input devices send information in and output devices send it out.
- Computers follow the pattern input, process, output.