Networks and connectivity in the classroom: a teacher's guide

5G

In plain English

The fifth generation of mobile network technology, used by phones and by connected machines.

Think of it like this

The latest version of the school's app: it does the same job as before, with new features, and old phones may not run it.Where that stops working: Having 5G on a phone does not mean you always get a faster connection. It depends on the mast, the signal and how many others are on it.

At work

Radio planning engineers and field engineers deploy and tune it.

Access point

In plain English

A device on the ceiling or wall that gives devices a radio connection into the wired network.

Think of it like this

A tuck shop hatch: it is where the outside world meets the system, and the queue gets long if it is shared by too many.Where that stops working: A hatch serves one person at a time. An access point serves many, and gets slower as it does.

At work

Network technicians install them, often one for each classroom or a few per floor.

Backbone

In plain English

The main high-capacity links that connect the big parts of a network, such as one city to another or a company's data centres to each other.

Think of it like this

The main corridor that connects every wing, while the small corridors only connect rooms.Where that stops working: A main corridor is still one corridor. Real backbones have several routes so that one failing does not cut everything off.

At work

Network architects design them, and when one fails it is a big story, as the first of our two true stories shows.

Bandwidth

In plain English

How much data a connection can carry in a second. It is usually written in megabits per second.

Think of it like this

The width of a corridor between lessons: wider lets more students through at once.Where that stops working: A wide corridor does not make anyone walk faster. Bandwidth is not the same as delay.

At work

Network engineers plan how much a site needs and what happens when everyone arrives at once.

Broadband

In plain English

A connection to the internet that is always on and fast enough for everyday use. It can be delivered over full fibre, cable or copper.

Think of it like this

The main supply pipe into a building: everything else depends on what size it is and what it is made of.Where that stops working: A pipe is one size all the way. A broadband speed is the most you might get, and what you get depends on the time of day and who else is using it.

At work

Field engineers build it, and planning officers decide where it goes.

Chamber

Also called: pit, manhole

In plain English

An underground box in the street, or a cabinet at the roadside, where cables can be reached for jointing or repair.

Think of it like this

An inspection hatch on a pipe: the one place you can get at it without taking the floor up.Where that stops working: A real chamber can be deep, wet and in the road, which is why opening one is a planned job with traffic and safety arrangements.

At work

Field engineers choose which chamber to open to reach a fault.

Data centre

In plain English

A building full of computers and the cooling, power and network connections that keep them running. Much of what people call the cloud is run from them.

Think of it like this

The school kitchen: you do not see it, but if it stops, nobody has lunch.Where that stops working: A kitchen feeds one school. A data centre serves millions of people in many places at once.

At work

Network and infrastructure engineers connect and protect them, and the government counts data centres as part of the communications sector of critical national infrastructure.

DNS

Also called: Domain Name System

In plain English

The system that turns a name you can remember, such as a website's address, into the number a network uses.

Think of it like this

The school office looking a student's name up in the register to find their form room.Where that stops working: The register lives in one place. DNS is spread across many servers that pass on questions to one another.

At work

It is a common first place to look when 'the internet is down' turns out to be one service, because if names stop working nothing seems to.

Ethernet

In plain English

The standard way of connecting devices with a cable, in offices, schools and homes.

Think of it like this

The wired phone line in the office that always works, compared with the mobile that sometimes does not.Where that stops working: It needs a cable to every device, which is why people prefer Wi-Fi even when it is slower.

At work

Network cable installers put it in, test it and certify it.

Failover

Also called: backup connection, redundancy

In plain English

A spare part or route that takes over automatically when the main one fails.

Think of it like this

A substitute teacher who walks in the moment the usual one is off, without anyone sending for them.Where that stops working: A substitute is only a substitute if they know the lesson. A failover that has never been tested may not work when it is needed.

At work

Network engineers design it and test it, and the DfE's school broadband standard asks for it.

Fibre-optic cable

Also called: fibre, optical fibre

In plain English

A cable with a very thin core of glass. Light carries the data along it and is kept inside the core by the glass around it, by total internal reflection.

Think of it like this

A torch beam in a long mirrored tube: it stays inside however the tube bends, within limits.Where that stops working: The light in a fibre is pulsed on and off in a pattern that carries the data, and it does not escape from the sides.

At work

Fibre technicians splice and test it, and subsea cable engineers lay it across the sea.

Filtering and monitoring

In plain English

Filtering blocks harmful or inappropriate content before it is seen. Monitoring watches what users do on devices and reports concerns afterwards. They are different, and a school needs both.

Think of it like this

A locked cupboard stops a student taking something. A member of staff on duty in the corridor notices what happens.Where that stops working: No filtering system can be 100% effective, which is why the DfE standards also ask for monitoring and a person who owns it.

At work

IT teams set it up, and the designated safeguarding lead makes sure it meets the school's safeguarding needs.

Firewall

In plain English

A device or program that checks traffic against a set of rules and decides what to allow in or out.

Think of it like this

The school gate with a member of staff on it, who knows who is allowed in.Where that stops working: A gate stops a lot, but not someone who is already inside, which is why networks also check what happens within.

At work

Network security engineers and firewall administrators configure and review them.

Full fibre

Also called: FTTP, fibre to the premises

In plain English

A connection where glass fibre runs all the way into the building, with no copper on the last stretch.

Think of it like this

A motorway all the way to the school gate, not a motorway that ends in a country lane.Where that stops working: A gate does not slow a motorway. The speed you get also depends on the equipment at both ends and the service you pay for.

At work

Telecoms field operatives and fibre jointers connect it, and it is what the DfE's school broadband standard asks for.

Internet

Also called: the web

In plain English

The worldwide collection of networks that are joined together. The web is one service that runs on it, and so are email and video calls.

Think of it like this

The road system is the internet. A shop, a school and a hospital are services that use it.Where that stops working: Roads are one kind of thing. The internet is made of cable, radio and software, and it is run by many separate organisations, not one.

At work

Almost every job in the field is about keeping some part of it joined to the rest.

IP address

In plain English

The number that identifies a device on a network, so packets know where to go.

Think of it like this

A postal address: it says where to deliver to, not who lives there.Where that stops working: A house keeps its address for life. A device's address can change, for example when it joins a different Wi-Fi.

At work

Network engineers plan the addresses a whole organisation uses so that none of them clash.

LAN and WAN

Also called: local area network, wide area network

In plain English

A local area network covers a small area such as a building. A wide area network covers a big one, such as links between towns. The internet is the biggest wide area network.

Think of it like this

A LAN is the school's own corridors. A WAN is the bus routes between schools.Where that stops working: A bus route is run by one company. A WAN can be built from links owned by many.

At work

LAN and WAN specialists are one of the jobs the Career Matrix lists for network engineering.

Latency

Also called: delay, ping, round trip time

In plain English

How long a packet takes to get there, or there and back. It depends on distance, because light takes time, and on every device on the way.

Think of it like this

How long it takes a note to be passed along a row, however wide the corridor is.Where that stops working: A note passed along a row loses time at each person. Light in a cable loses time per kilometre, and each router adds a little more.

At work

It is why companies pay for shorter cables and why online games ask which server is nearest.

Mast

Also called: cell site, tower

In plain English

A tall structure with antennas and radio equipment that connects phones to the mobile network.

Think of it like this

The tall lamp-post with the loudest speaker in the playground: it is high so that everyone in range can hear it.Where that stops working: A speaker only sends. A mast also listens to every phone near it, and passes what it hears on by fibre or radio.

At work

Cellular network field engineers and wireless communications riggers install and maintain what is on them.

Megabit and megabyte

Also called: Mbps, MB

In plain English

A bit is the smallest piece of data, and a byte is eight of them. Speeds are usually quoted in megabits a second and files in megabytes, so the two need converting.

Think of it like this

Pounds and pence: the same money written two ways, and easy to mix up if you do not look at the unit.Where that stops working: A pound is always 100 pence. A megabyte is eight megabits, a different factor, so the sum is different.

At work

Engineers quote capacity in bits and customers think in files, so they convert all the time.

Network

In plain English

Two or more devices connected so they can share information, by cable or by radio.

Think of it like this

The school's group chat: everyone in it can reach everyone else, and it stops being useful the moment it is cut off from the rest.Where that stops working: A chat is one group. A real network is many groups joined to other groups, and joined to those.

At work

Network engineers design, install and look after them, and NOC analysts watch them for trouble.

OTDR

Also called: optical time domain reflectometer

In plain English

A fibre tester. It sends a short pulse of light down a cable and times the reflections that come back, which shows the length and where any joints, losses and breaks are.

Think of it like this

Shouting into a long tunnel and timing the echo to tell how far away the end is.Where that stops working: An echo gives you one number. An OTDR draws a whole trace with every joint and break on it.

At work

Field engineers use it to find faults without digging up the whole route.

Packet

In plain English

A small piece of a message, with an address on it. A big message is cut into many of them, and they are put back in order at the other end.

Think of it like this

A long letter sent as separate numbered postcards, each with the address on, which the receiver puts back in order.Where that stops working: Postcards take days. Packets are far quicker, and a lost one is simply sent again without anyone noticing.

At work

Network engineers work out what happens to packets when a link is busy, and security engineers look at which ones should be let through.

Protocol

In plain English

An agreed set of rules for how two devices talk to each other, such as how to start a conversation, how to number the pieces and how to say they arrived.

Think of it like this

The rules of a debate: who speaks first, how long you get, how you say you disagree.Where that stops working: Debate rules can bend. A protocol that is followed even slightly differently by two devices usually means they cannot talk at all.

At work

Almost every networking job needs to know which protocol is involved when something fails.

Router

In plain English

A device that looks at the address on each packet and chooses the next step on its way, and links one network to another.

Think of it like this

A teacher at a corridor junction pointing each student towards the right classroom.Where that stops working: A router decides millions of times a second, and it only knows the next step, not the whole route.

At work

Network engineers configure routers, and a wrong setting on one can take a whole site offline.

Single point of failure

In plain English

One part that everything depends on, so that if it fails nothing works.

Think of it like this

The only door to a hall: if it jams, nobody gets in or out.Where that stops working: A second door helps only if it opens onto a different corridor. Two doors that both lead through one bottleneck are still one point of failure.

At work

Network engineers look for them in every design and fix them by adding a different route or a backup.

Splice

Also called: joint, jointing

In plain English

Joining two ends of fibre or cable so that the signal goes through with as little loss as possible.

Think of it like this

Joining two ropes so smoothly that a climber cannot tell where the join is.Where that stops working: A rope join only has to hold. A fibre joint has to carry light, so a tiny speck of dust matters.

At work

A core skill in the telecoms field operative and fibre jointer jobs.

Structured cabling

Also called: cable installation

In plain English

The tidy, planned cabling inside a building: cables to every room, joined at a hub, labelled, tested and certified.

Think of it like this

The electrics of a school: hidden in the walls, planned before the building opens and expected to last for decades.Where that stops working: Electrics work or they do not. Network cabling has to be tested to show it meets a standard, and the result is certified.

At work

Network cable installers do it, and the DfE standards say what school cabling should meet.

Subsea cable

Also called: submarine cable, undersea cable

In plain English

A fibre-optic cable laid on the seabed to link countries and carry their internet traffic.

Think of it like this

The bridge between two islands: if it closes, everything that crosses it stops or has to go the long way round.Where that stops working: A bridge is above water and can be seen. A cable lies on the seabed and has to be found and lifted by a ship to repair.

At work

Submarine cable engineers lay them, and cable ship crews repair them.

Switch

In plain English

A device that connects the devices inside one network, such as the computers in a room, and passes each packet to the right one.

Think of it like this

The corridor outside the classrooms: it joins every door in one building to every other.Where that stops working: A corridor lets everyone hear. A switch sends each packet only to the device it is for.

At work

Network technicians install and manage them in cabinets and comms rooms.

TCP/IP model

Also called: layers

In plain English

A way of describing what happens to a message in four layers: the application, the transport, the internet and the link. Each layer does one job and hands the result to the next.

Think of it like this

An assembly line for a letter: someone writes it, someone numbers the pages, someone writes the address and someone puts it in the van.Where that stops working: A real network does not stop at four neat steps, and some descriptions use more layers. It is a way to think, not a law.

At work

Engineers use the layers to narrow down a fault: is it the app, the addressing, the link or the cable?

VPN

Also called: virtual private network

In plain English

A way of sending data through a protected tunnel across a public network, so that it is encrypted on the way.

Think of it like this

A sealed envelope inside the school bag: the bag can be seen but not the letter.Where that stops working: A sealed envelope still has a name and address on the outside. A VPN hides what is sent but not that a connection exists.

At work

VPN specialists set them up so that staff can work from anywhere, and a school's filtering has to deal with students using their own.

Wi-Fi

Also called: wireless

In plain English

A way of connecting devices to a network using radio instead of a cable, over a short distance.

Think of it like this

Shouting across a room: it works, but a wall muffles it, and ten people shouting at once makes it harder for everyone.Where that stops working: Radio is not literally shouting, and a good network uses several carefully placed access points rather than one loud one.

At work

Wireless engineers survey buildings, place access points and choose radio settings so that coverage reaches everywhere it is needed.