Computer Networks

What are computer networks?

A computer network is a collection of interconnected computer systems which ‘talk’ to each other by exchanging data. Connecting computers to form computer networks has had a huge impact on our lives. The internet is a network of networks. Think how limited our use of technology in school would be without it. Think how frustrating it is when we have no data signal for our smartphones, or no Wi-Fi for our laptops.

The computer network within your school possibly consists of only a few computers. Networks of this size are called local area networks (LANs). The following diagram shows the devices comprising a typical LAN; the three devices in the centre of the picture are typically combined in a home network (see below).

Diagram showing a typical layout of devices in a local area network.

The layout of devices in a LAN.

A LAN enables:

the management of user accounts;

the running of software;

the facility to save documents to a shared area;

printing;

access to the internet.

A server.

A client is any computer system on a network which uses the services provided by the server. For example, each classroom might have a computer at the front of the class which is linked to the school’s LAN and which is used with an interactive whiteboard. Teacher and pupil laptops will also likely be configured to access a school’s LAN to enable internet access, printing and the saving of work to a shared area. Other devices such as tablets or phones may also be clients, since these too can connect to the LAN.

Images of client computers in networks.

Possible clients in a network.

Switches and hubs are used to connect the various devices on a network, reducing the amount of cabling required.

A photo of a school's server.

A server in a school's LAN.

A modem provides access to the internet by converting the format of data in computer systems to one which can be transmitted along telephone lines to your internet service provider (ISP). It also performs the reverse conversion for data coming in from your ISP.

A range of devices may connect to a LAN wirelessly. These could be clients, such as laptops, tablet devices and phones. Devices providing services to the network (e.g. printers) may also connect wirelessly. A wireless router enables devices to connect to the LAN by routing data across a wireless connection.

Wide area networks (WANs) are created when lots of smaller networks are connected together. The largest WAN of all is the internet. Note that the internet is a physical thing: it’s the cables and fibres, transmitters and receivers, switches and routers – and all the rest of the hardware infrastructure – which connect networks of computers together. The World Wide Web is the information on the internet, displayed as web pages whose content is stored on web servers and viewed across the internet using web browsers such as Internet Explorer, Google Chrome and Mozilla Firefox. So, the World Wide Web is one example of an internet service.

The internet has been designed to do one job: to transport digital data between computers. This information might take the form of a web page, an email or a video call but all of it is in binary code consisting of strings of the digits 0 and 1, transmitting as on/off or high/low electrical or optical signals. Binary code is similar to the Morse code used for the telegraph in Victorian times, but it’s much, much faster. A good telegraph operator could work at maybe 70 text characters per minute, but even a basic school LAN can pass data at 100 million on/off pulses per second – sufficient for some 12.5 million characters per second. One transatlantic fibre connection has the capacity for up to 400 billion characters per second!

To be sent efficiently, digitised information is broken down into small chunks – data packets – which pass quickly through the internet and are reassembled at the receiving computer. These packets can take any route from sender to recipient, although there’s generally a most efficient route which all the packets take. The process happens so quickly that high-definition video can be streamed from the internet, normally without any glitches.

A map of a network featuring seven routers between two servers, showing the simplest route.

A sample network. (From "QuickStart Computing: a CPD toolkit for Primary teachers".)

When you type a URL address (such as www.bbc.co.uk) into your web browser, you send a packet of data requesting that the content of that page be returned to you over the internet. For this to happen, the Domain Name Service (DNS) converts the requested URL into a numeric IP (Internet Protocol) address; the DNS itself uses the internet to look up this numeric address in the equivalent of huge phone books. The requested web page content again consists of data packets, each of which carries a destination IP address. So, routers can easily and correctly pass on each packet.

The journey of a packet of data from your home computer to one of Microsoft’s server farms might look something like this (from “QuickStart Computing: a CPD toolkit for Primary teachers”):

Diagram showing the stages of sending a packet of data between the UK and a server farm in the USA.

The journey of a packet of data from your computer to one of Microsoft's server farms. ("From QuickStart Computing: a CPD toolkit for Primary teachers".)

To be able to send sensitive information – such as passwords or bank account details – secretly via the internet, it’s important to encrypt the data first. (It will be decrypted when it reaches its destination.) This happens automatically when using web addresses commencing “https” (HTTP Secure) – you’ll see a little padlock displayed in your browser’s address bar.

Why are computer networks important?

Computer networks enable multiple computer systems to share software, printing, internet access and an area for saving files, reducing organisational costs. Networks facilitate file-sharing and collaboration. Servers can be set up to create automatic backups of content stored across a network. The internet itself provides a wide range of services which we use and depend upon daily. The term “Internet of Things” has been coined to describe the multitude of computing devices embedded in goods and networked to the internet. One example is the thermostat which can be controlled using your mobile phone. South Korea’s Songdo International Business District is a “smart city” where sensors throughout collect data which feeds back to the management of resources and assets. Looking to 2020, Gartner has estimated that there’ll be nearly 26 billion devices on the Internet of Things, whilst ABI Research has proposed there may be 30 billion devices wirelessly connected to it (the “Internet of Everything”).

What do computer networks look like in the Primary curriculum?

Learning about computer networks isn’t referenced until Key Stage 2; however, throughout EYFS and Key Stage 1, pupils will likely be surrounded by a school’s LAN. They might have login details to access this network, and know about the process of accessing the internet. We can make our pupils aware that devices are connected (networked) together and start to talk about why this might be. It may be useful to use analogies to other networks pupils are familiar with, such as family trees or the road and rail systems. We can explain how being networked lets us share things, whether this be chatting with relatives or moving food from one city to another. At Key Stage 2, much of the understanding of how computer networks operate can be taught through unplugged drama-based activities, where pupils take on the role of the various network components and learn about their functions. Developing understanding of computer networks underpins subsequent learning about such network services as email and search engines.

3 - 5 years

Computers and mobile devices are often used in roleplay environments. As teachers, we can model this technology, pretending to send messages across the world to people we know, giving an opportunity to talk about how devices are connected and how to stay safe on the internet. Pupils develop an understanding that computers in their school are connected to one another and to computers in the world beyond the gates.

5 - 7 years

Pupils learn that computers and other school devices are connected to form a network – illustrate this by showing them the switches, hubs and connecting wires. The children gain experience in requesting access to this network by logging in with a username and a password. They use a variety of computer systems and see that some of the same software can be accessed across these, that they can print to the same printer from different locations, and that they can save work and re-open it in a common area on the network. They start to understand that the computers within their school network are connected to computers across the world as part of the internet. They become familiar with using a web browser and learn about the safe and responsible use of this technology.

7 - 11 years

Pupils build further their experience of using a range of computer systems to access a variety of services on their school’s network. They learn about the different hardware components of a LAN. One activity is to take them on a hunt around the school to locate devices such as the server, switches, hubs, client computers and printers. In so doing, they’ll learn about the role each of these plays within the network, and about the benefits of networking computer systems. To understand that the internet is a vast network of networks of computers and devices, connected across the planet, they can use visual trace-route tools like http://en.dnstools.ch/visual-traceroute.html to track the global location of a web server within which the content for a particular web page is stored. They can also complete unplugged activities, such as making a 'human model' of the internet.

Find out more about computer networks / Downloads

Computing At School (2015): “QuickStart computing – a CPD toolkit for Primary teachers” (opens in a new window)

Video explaining the difference between the internet and the World Wide Web (opens in a new window)

Wikipedia page explaining the history of the internet (opens in a new window)

Computing At School (2013): “Computing in the national curriculum – a guide for Primary teachers” (opens in a new window)

Planning from Phil Bagge to support teaching the concepts of the internet and World Wide Web (opens in a new window)

Video of pupils at Winchester House School explaining how the internet works (opens in a new window)

Activities that are great to get you started:

These activities develop pupils' understanding of computer networks.

Network Hunt Activity

Age:7-11 years
Concepts / Approaches: Computer Networks
Curriculum Links: Geography

Pupils go on a hunt around their school to discover, and map the location of, devices connected to their school’s network. They then learn about the role of each device by either conducting web-based research or using the matching activity included.

The Network Hunt Activity has been rated 5 stars

Modelling the Internet

Age:9-11 years
Concepts / Approaches: Internet Services, Abstraction, Computer Systems, Computer Networks
Curriculum Links: Geography

Pupils learn that the internet is a vast network of computers and other devices connected across the world, as they explore the difference between the internet and the World Wide Web (WWW).