Objectives
By the end of this lesson you will be able to…
- Understand the difference between a LAN and a WAN, and give examples of each.
- Know the hardware required to build a LAN: NIC, switch, router and wireless access point.
- Identify different network topologies, including bus and star.
- Compare the advantages and disadvantages of each topology.
Starter
Computers in a school can be connected to a network. Discuss with a partner:
- What are at least three advantages of doing this?
- What are at least two disadvantages?
Click each card to reveal a suggested answer.
✅ Advantages
⚠️ Disadvantages
Local Area Network (LAN)
A LAN is a group of computers and devices connected together in a small geographical area — like an office, school, library or home.
Wide Area Network (WAN)
A WAN is created when two or more LANs are connected together — usually over a long distance using leased lines (dedicated telecommunications cables).
🔗 What is a leased line actually made of?
Remember from Lesson 2 — data has to travel through some kind of physical medium. A leased line is just a posh name for a dedicated cable rented from a telecoms company.
Fibre optic
Most modern leased lines are fibre optic — pulses of light through glass strands. Very fast and reliable over long distances.
Copper (twisted pair)
Older or shorter leased lines may still use copper twisted pair — cheap, but slower and limited in distance.
Submarine cable
For WANs that cross oceans, the data travels along submarine fibre-optic cables on the seabed (160 Tb/s — Lesson 2!).
🛰️ Where does an ISP fit in?
Big companies can afford to rent a leased line just for themselves. What about your home? Click each step to follow the journey.
Network Interface Card (NIC)
Every device that joins a network needs a NIC. It's the part of the computer that physically connects it to the network — either by cable or by radio waves.
Network topologies
A topology is the way the parts of a network connect together. It doesn't show where things physically are — only how they're linked.
Analogy: London Underground map
A tube map shows you which stations connect to which lines. It doesn't tell you exactly where each station sits in the real world.
Network topologies work the same way: they show connections, not physical positions.
There are many network topologies. In this lesson we'll look at two of the most common:
Bus networks
A bus network has one main cable (the "bus") which every device connects to. A terminator sits at each end to stop the signal bouncing back.
💡 Click "Send data" to watch a packet travel along the bus. Then try cutting the cable!
Advantages & disadvantages
Discuss two of each with a partner, then click to reveal.
✅ Advantages
⚠️ Disadvantages
Star networks
A star network has a central switch (or hub). Every device connects to it with its own cable. To add a new device, you just plug it into the switch.
💡 Click a cable in the diagram to break it. See what happens — only one device loses its connection!
Advantages & disadvantages
Discuss two of each with a partner, then click to reveal.
✅ Advantages
⚠️ Disadvantages
Side-by-side comparison
Click each row to compare bus vs star. The green badge shows which one is better for that category.
Only one main cable and two terminators are needed.
Every device needs its own cable running to the switch — plus you have to buy the switch.
If the main cable breaks, every computer loses its connection.
If one cable breaks, only that one device goes offline — the rest of the network keeps working.
All devices share the same cable, so bandwidth drops as more computers are added.
Each device has its own dedicated link to the switch — no sharing.
Just tap into the main cable at the new device's location.
You have to run a new cable all the way back to the switch.
Just two terminators on the ends of the cable.
A switch or hub is essential — and if it fails, the whole LAN fails.
🚌 Pick a bus when…
You want a cheap network with very few computers, and reliability isn't critical.
⭐ Pick a star when…
You need speed and reliability — like a school, office or modern home network.
Routers, switches & access points
A LAN is built from several pieces of network hardware. Click each card to find out what it does.
🏠 In real life: 2-in-1 (and 3-in-1!) boxes
In school we look at a switch, a router and a wireless access point as three separate devices — because each one does a different job. But at home, your ISP gives you a single black box that combines them all:
- Router — to connect your home LAN to the internet
- Wireless Access Point — to broadcast your home Wi-Fi
- Switch — usually 4 yellow Ethernet ports on the back to plug in wired devices
That's why your "Wi-Fi router" has antennas and Ethernet ports — it's really three devices in one case.
Plenary
Work with a partner. Match each networking word on the left to its definition on the right.
Key terms
Click each term to reveal its definition.
🎉 End of Lesson 3