KS3 · Computer Science

Introducing computer networks

Press print at school and your computer becomes a client. A client of what? Tap around this network and find out who does what.

Computer Science · Structure

One school network, every box with a job

Tap each box to see what it does. Ethernet cables send data as electrical signals; fibre optic cables send it as light pulses.

Tap any part of the diagram to see what it does.

Computer Science · Networks

What is this device doing?

Decide first, then read why. Is each description a client, a server or a router?

Still to sort

Client (0)

Asks for a service.

Where the line is: If a device sends a request to a server, it's a client.

Server (0)

Provides a service to clients.

Where the line is: A server provides a service such as storing files or webpages. It doesn't connect networks together.

Router (0)

Connects different networks.

Where the line is: A router joins different networks and directs data between them. It isn't providing files, pages or printing.

6 of 6 still to sort.

Computer Science · Networks

Which idea sounds like yours?

Four pupils are looking at the school network diagram and each says something different.

Which one is closest to what you think right now?

"Clients, servers and routers are basically the same. Any of them could do the others' jobs.""A router's job is to move data around between the computers inside the school.""The router is just another server. It stores the files and webpages for everyone.""Each one has its own job: clients request, servers provide, and a router connects different networks and directs data between them."

How sure are you?

I'm sureI think soI'm guessing

"Clients, servers and routers are basically the same. Any of them could do the others' jobs."

This is a common misconception

Easy mistake, because they're all devices on the network. But they have distinct roles and aren't interchangeable: a server provides services, a client requests them, and a router connects networks and directs data between them.

"A router's job is to move data around between the computers inside the school."

This is a common misconception

This wording does the rounds, which is why it catches people out. A router connects different networks and directs data between them. It's the link between this network and others, such as the internet.

"The router is just another server. It stores the files and webpages for everyone."

This is a common misconception

Servers are the ones that provide a service, such as storing files or webpages. A router doesn't do that job. It connects different networks and directs data between them.

"Each one has its own job: clients request, servers provide, and a router connects different networks and directs data between them."

This matches the evidence

Yes. Three different roles, and that's why each one gets its own box on the diagram.

Clients ask, servers provide, and the router joins one network to another.

Why share?

Reason it through

Why does one shared printer save a school money and space?

Link 1 of 3

First link · your turn

What does the print server do when someone sends a print job?

Locked — reveal the link above first

Predict, then check

Think about where Maya's work is while she's away from her desk.

Maya saves her coursework on a computer in Room 4. Next day she sits at a different computer in the library, on the same school network. Can she open it?

Computer Science · Networks

Put the benefits in your own words

Your school has one local network joining its classroom computers, servers and a router. Describe four benefits it gives the people who use it. [4 marks]

Your answer

0 words · your answer stays on this page and is not sent anywhere.

The mark scheme

Users can access their files and work from any computer on the network, so they aren't limited to one machine. (1 mark)
Expensive devices such as printers can be shared between users, which saves money and space. (1 mark)
Users can share files and work together on the same document, even from different rooms, as long as they are connected to the network. (1 mark)
User activity can be monitored to help keep the network secure and prevent unauthorised access. (1 mark)

Model answer

On a school network you can open your work from any computer, so you're not stuck with one machine. Printers and other expensive devices can be shared by lots of users, which saves money and space. Pupils can share files and work on the same document from different rooms, as long as they're connected to the network. The school can also monitor what users do on the network, which helps keep it secure and prevents unauthorised access.

Four benefits: reach your work anywhere on the network, share devices, share files and collaborate, and monitor to stay secure.

WHAT YOU'VE LEARNED

A quick recap of today's lesson.

Clients ask. Servers provide. The router joins your network to other networks.

What you need to know

A computer network is two or more devices connected together so they can communicate, by cable or wirelessly.
You'll find networks in homes, schools and offices. Local networks can also give access to the internet.
Network hardware is the equipment that lets data travel across a network. Different devices do different jobs.
A server is a computer on a network that provides a service, such as storing files or webpages.
A client is a device that requests a service. Send a request to a server and you're the client.
Have a goA teacher's laptop asks a server for a page of the school website. Which device is the client?
The teacher's laptop.
It's the one sending the request. The server is the device that provides the page.
A router connects different networks and directs data between them. It can link a local network to the internet.
Have a goThe school wants its network to reach the internet. Which device does that: print server, router or classroom computer?
The router.
A router connects a local network to other networks. Servers provide services and classroom computers request them.
Ethernet cable sends data as electrical signals. Fibre optic cable sends it as pulses of light.
Have a goData is travelling down a cable as flashes of light. Is that Ethernet or fibre optic?
Fibre optic.
Fibre optic cable uses light pulses as signals. Ethernet uses electrical signals.
On a local network you can open your files and work from any computer on it.
Expensive devices like printers, scanners and servers can be shared by many users. That saves money and space.
Connected users can share files and collaborate on one document, even if they're in different rooms.
A network can monitor user activity. That helps prevent unauthorised access and keeps the network safe.

The big picture

A computer network joins two or more devices so they can communicate, using cables or wirelessly. On a simple network, clients request services, servers provide them, and a router connects the network to other networks. Ethernet and fibre optic cables carry the data, and a local network lets users share devices and files, reach their work from any computer and be kept secure.

Key points

1A network is two or more devices connected, by cable or wirelessly, so they can communicate.

2Clients request services, servers provide them, and routers connect different networks and direct data between them. These roles are not interchangeable.

3Ethernet uses electrical signals and fibre optic uses light pulses to carry data.

4A local network lets users reach their work from any computer, share expensive devices, share files and collaborate, and be monitored to stay secure.

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Worked example

Problem

Break time. Leo's computer asks for his saved art project and the file opens. A few minutes later it asks for a web page that isn't on the school network, and the page loads. Which device plays which role?

⚠ Watch out

Judging a device by what it looks like instead of what it's doing. If a device sends a request to a server, it's the client, whatever kind of computer it is.

🧠

Memory hook

Clients ask. Servers serve. Routers join networks. Three jobs, three kinds of box.

✓

Check yourself

Cover the page. Name the three roles on a simple network and give each one a one-line job description.

Flashcards

(13)

What is a computer network?

A group of two or more devices connected together, wirelessly or using cables, so they can communicate.

What is network hardware?

The components on a network that let data be transmitted across it. Devices perform different roles to exchange information.

What is a client?

A device on a network that requests a service from a server.

What is a server?

A computer on a network that provides a service to clients, such as storing files or webpages.

What does a file server do?

Stores files and provides access to them, and manages requests to create, edit and delete files.

What does a print server do?

Manages requests for a network printer when a user sends a print job.

What does a web server do?

Hosts the pages and files needed for websites.

What does a router do?

Connects different networks together and directs data between them. It can connect a local network to the internet.

How does Ethernet cable carry data?

Using electrical signals.

How does fibre optic cable carry data?

Using light pulses as signals.

Can a client, a server and a router swap jobs?

No. They have distinct roles and aren't interchangeable.

Why is sharing expensive devices on a network useful?

Printers, scanners and servers can be shared between many users, which saves money and space.

Why might a network monitor what its users do?

It helps prevent unauthorised access and keeps the network safe.

Tap any card to flip it, or use Study as deck to go through them one at a time. In the full lesson these run as a spaced-repetition deck — you rate each card Hard, Good or Easy and the tricky ones keep coming back until they stick.

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One school network, every box with a job

What is this device doing?

Which idea sounds like yours?

Put the benefits in your own words

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