What Is a Network?

Lesson plan

Level

Beginner

Time

About 70 minutes; the steps below add up to 71

The first networking lesson, built around one fictional school and one print job. Learners diagnose a printer that prints symbols before the word protocol appears, trace a print job through the four elements inside two devices, and work out how a wired and a Wi-Fi device each join the network before the network interface card and MAC address are named. They picture the school's devices on a map, then discover the difference between a switch and a router by predicting and tracing two journeys on a star diagram, and trace the laptop's print job step by step on the map. They sort the devices into hosts and nodes, name network sizes, and finish with security: a connection is a route, not permission, and every connected device is a possible way in. The habit to build: when devices cannot talk, ask which element is failing; when data moves, ask which devices it passes through and whether it leaves its own network.

Objectives

• Explain what a network is and why it needs agreed rules (protocols)
• Name the four elements of a network conversation
• Describe the roles of endpoints, servers, switches and routers, and tell a host from a node
• Describe networks by scope: PAN, LAN, MAN and WAN
• Explain why connecting to a network does not automatically grant access to its resources, and identify basic network security risks

Before the lesson

• Open this page on your own screen and use “Open the lesson window” to open the lesson in a second window. Share only that second window.
• Each step opens with a question and reveals one teaching moment per press of Next. On the two traced routes, each press moves the route on by one device; the route's own buttons are hidden while presenting, so there is one set of controls. The status line under the buttons on this page says what is on screen and what Next will show.
• The lesson takes about 70 minutes. To teach it in two parts, stop after “Switches and routers” (about 35 minutes: what a network is, network interface cards, the school's devices, and switches and routers) and start the second part with “Following a print job”, which recaps the map. The lesson page stays one lesson; use “Show this step” to start the second part.
• If you can, bring a network cable, and a photograph of a switch, an access point and a home broadband box. The home box is useful in “Switches and routers”.
• No prior knowledge is assumed. Decide whether the “Apply it” questions are done in the lesson or set for another day.

Steps

1. Introduction Opening

   On screen: the lesson’s title, module and number; Next adds its objectives and key terms, as the lesson page lists them; Next again begins the first step.

   Objectives on screen

   • Explain what a network is and why it needs agreed rules (protocols)
   • Name the four elements of a network conversation
   • Describe the roles of endpoints, servers, switches and routers, and tell a host from a node
   • Describe networks by scope: PAN, LAN, MAN and WAN
   • Explain why connecting to a network does not automatically grant access to its resources, and identify basic network security risks

   Purpose: The first networking lesson, built around one fictional school and one print job. Learners diagnose a printer that prints symbols before the word protocol appears, trace a print job through the four elements inside two devices, and work out how a wired and a Wi-Fi device each join the network before the network interface card and MAC address are named. They picture the school's devices on a map, then discover the difference between a switch and a router by predicting and tracing two journeys on a star diagram, and trace the laptop's print job step by step on the map. They sort the devices into hosts and nodes, name network sizes, and finish with security: a connection is a route, not permission, and every connected device is a possible way in. The habit to build: when devices cannot talk, ask which element is failing; when data moves, ask which devices it passes through and whether it leaves its own network.

2. 1. Connected, but not communicating Think 5 min

   Purpose: Discover that a connection is not enough: devices need shared rules. The word protocol comes after the class has reasoned its way to the idea.

   Ask

   • The printer woke up and printed every page. So did the data reach it?
   • If every page arrived but makes no sense, did the problem happen on the way, or in understanding?
   • What would two people on a perfectly clear phone line still need?

   Responses to expect

   • Many pick the cable first: damage feels like the obvious cause. Ask what damaged data usually looks like (missing pages, nothing at all) and compare it with neat pages of symbols.
   • A few say the internet; use it to show early that the laptop and printer are joined directly.
   • On screen in turns: the question, then its answer with the telephone comparison, then where the comparison stops.

   Misconceptions to challenge

   • A learner may believe: “If it is plugged in, it should work.” Respond: Plugged in means signals can arrive. Ask what the printer has to do with them before anything prints.

   Discussion pause: Take a vote on the three options before anyone presses Check. Ask a supporter of each to argue for it.

   If the explanation does not land: Hand a learner a note written in a code they do not know. It arrived perfectly; can they act on it?

   In the lesson window

   • Think it through: A laptop is joined to a printer by a working network cable. When the teacher prints a worksheet, the printer wakes up at once but prints only pages of random symbols. What is most likely missing?

3. 2. What a network is and why it exists Explain 7 min

   Purpose: Separate the document, the print job and the printed worksheet, name the four elements by tracing a print job, define a network, and read the diagram as a path down one device, across the media and up the other.

   Ask

   • Does a sheet of paper travel from the laptop to the printer? What does?
   • Before any names: what has to happen inside the laptop, between the devices and inside the printer?
   • On the diagram, trace the print job with your finger. Which element would a broken cable affect? The wrong printer software?

   Responses to expect

   • Some beginners picture the worksheet itself travelling. Settle the three words early: the document is on the laptop, the print job travels, the worksheet comes out on paper.
   • Learners name the program and the cable quickly and miss the protocol and the network card. The hints lead to them.
   • Diagram guidance: each device is drawn with the application at the top and the network interface card at the bottom, because data is handed down inside the sender and back up inside the receiver. The middle box is everything between them, opened up later in the lesson.
   • On screen in turns: the answer naming the four elements, the definition of a network, the diagram on its own, the numbered journey, then what the diagram does not show.

   Misconceptions to challenge

   • A learner may believe: “The protocol is a part inside the computer.” Respond: It is a set of rules both devices follow; software applies them. Point back to the printer that printed symbols.

   Discussion pause: Let pairs list what has to happen before you reveal the answer, then compare their lists with the four elements.

   If the explanation does not land: Posting a letter: you write it (application), follow the address format (protocol), hand it to the post (network card) and the vans carry it (media).

   In the lesson window

   • Think it through: A teacher presses Print on a laptop, and a print job has to get from the laptop to the printer across the room. What has to happen inside the laptop, between the two devices, and inside the printer, before the worksheet comes out on paper?

4. 3. Network interface cards Discover 8 min

   Purpose: Work out that every networked device needs a part that sends and receives signals, see wired and Wi-Fi network interface cards side by side, then discover why each card needs its own identifying number before the MAC address is named.

   Ask

   • The office computer has a cable and the laptop has none. What must each have inside it?
   • On the diagram, point to the part of each device that does the connecting. What leaves each one?
   • The switch has to send a print job to the printer and nowhere else. How could it tell the printer apart?

   Responses to expect

   • Expect “the Wi-Fi” and “the cable” rather than a part of the device; ask what inside the device makes the signals.
   • For the MAC question, the printer's name is the common first answer. Ask what happens if two printers are given the same name.
   • Diagram guidance: the dashed box inside each device is its network interface card. A solid line is a cable and a dashed line is Wi-Fi; the words on each line say the same.
   • On screen in turns: the question, its answer, the diagram, Ethernet and Wi-Fi, the MAC address question and its answer, then the faulty-cable check and its answer.

   Misconceptions to challenge

   • A learner may believe: “Wi-Fi devices do not need a network card.” Respond: The card is built in. Wi-Fi is what that card sends and receives instead of signals on a cable.
   • A learner may believe: “A MAC address proves which person is using a device.” Respond: It identifies a network card on the local network, and can be changed in software. It is not proof of identity.

   If the explanation does not land: A house needs a front door to receive post, whatever road it is on; the network interface card is the device's front door, and the MAC address is the name on that door.

   In the lesson window

   • Think it through: An office computer has a network cable plugged into it. A teacher’s laptop has no cable at all. Both are on the same school network. What must each device have inside it so that it can send and receive data, and how does each one reach the network?
   • Think it through: Many devices are plugged into the school’s main switch. When a print job arrives for the printer, the switch has to send it to the printer and to no other device. What could the switch use to tell the printer’s network interface card apart from all the others?
   • Check your understanding: A teacher’s laptop works normally on the school Wi-Fi. When it is plugged into a network cable instead, it cannot reach anything, although the same cable and switch work for other computers. Which part of the laptop is most likely at fault?

5. 4. Devices, services and communication Discover 6 min

   Purpose: Picture the whole school network, name endpoints, servers and the wireless access point on a map, and leave the switch and router as a question for the next step.

   Ask

   • Picture the school's network: what other devices are there, and what does each do?
   • On the map, find the device the laptop connects to. What is it joined to?
   • The switch and the router both join things. Do you think they do the same job?

   Responses to expect

   • Learners often call every box a router. Do not settle it here: the map's last entry hands the question to the next step.
   • Diagram guidance: the map shows what is plugged into what, not importance. The router is at the top only because the internet line enters there.
   • On screen in turns: the question, its answer, the map with no explanations, endpoints and servers, the access point, then the switch-and-router teaser.

   Discussion pause: With the map on screen and no explanations yet, ask the class to guess the job of each kind of device before you reveal each one.

   In the lesson window

   • Think it through: The staff-room printer is one device on a school’s network. Picture the rest of that network. What other devices would you expect to find, and what job does each one do?

6. 5. Switches and routers Discover 9 min

   Purpose: Discover from two traced journeys that a switch joins devices within a network and a router joins networks, then define both and deal with the home broadband box.

   Ask

   • The office computer prints a letter. Does the print job need the router?
   • Before the second journey: the office computer opens a website. Which devices will the request pass through?
   • Why does the second journey need the router when the first did not?
   • Who has a box at home called the router? What jobs is it doing?

   Responses to expect

   • Most predict the first route correctly once they see both devices on the switch; the second journey is where “everything goes through the router” resurfaces in reverse, with some leaving out the switch.
   • Diagram guidance: the star puts the main switch in the middle so each route is a short chain of lines. The traced route is drawn with thicker lines and outlined boxes, not by colour alone.
   • On screen in turns: the question, its answer, the star diagram with no route, route A in two steps, the prediction for route B, route B in three steps, the definitions, the tablet check and its answer, then the home box.

   Misconceptions to challenge

   • A learner may believe: “Switches and routers do the same job.” Respond: Point at the two routes: the print job never touched the router; the website request had to. One joins devices, the other joins networks.
   • A learner may believe: “Every device that joins things is a router.” Respond: A home box combines a router, a switch and an access point, so the name sticks to the whole box. In a school they are separate devices.

   Discussion pause: Stop at the prediction for route B and take a show of hands for each device before pressing Next.

   If the explanation does not land: A school's internal post tray and the post office: notes between classrooms go through the internal tray (switch); letters to another address go out through the post office (router).

   To go further

   • Some larger switches can also route. What would such a device be doing when it sends data between two networks inside one organisation?

   In the lesson window

   • Think it through: In a school, the office computer and the office printer are both plugged into the main switch. The school’s router connects the school to the internet. When the office computer prints a letter on that printer, which device does the print job pass through on its way?
   • Check your understanding: A pupil’s tablet on the school Wi-Fi saves a file to the school server. The server is plugged into the main switch. Which statement about the file’s journey is accurate?

7. 6. Following a print job Predict 6 min

   Purpose: Apply the switch and router idea to the laptop's print job, then trace it device by device on the familiar map, including the access point bridging Wi-Fi onto the cable, and change one fact.

   Ask

   • Does the laptop's print job pass through the router? Talk the path through before the map appears: laptop, access point, switch, printer.
   • What does the access point do that the office computer's print job did not need?
   • If the printer is at another school across town, which devices join the route?

   Responses to expect

   • After the previous step most say no to the router; check that they can say why.
   • The second appearance of the map extends it: the route now starts with Wi-Fi, so it is one step longer than the office computer's.
   • On screen in turns: the question, its answer, the map with no route, each of the four route steps, then the result and the printer at another school.

   Misconceptions to challenge

   • A learner may believe: “Data on Wi-Fi always goes through the router.” Respond: It goes to the access point, which bridges it onto the cable. The router is only needed if the data leaves the network.

   To go further

   • The teacher prints to a printer at another school in the trust. Draw the route. How many routers does it pass, and why?

   In the lesson window

   • Think it through: A teacher’s laptop is on the school’s Wi-Fi, which reaches the main switch through a wireless access point. The staff-room printer is plugged into the same main switch by cable. When the teacher prints a worksheet, does the print job pass through the school router?

8. 7. Hosts and nodes Discover 6 min

   Purpose: Sort the devices on the route into those that used the print job and those that only passed it on, name them hosts and nodes, and apply the idea to a new device.

   Ask

   • Which devices on the route used the print job?
   • Is every host a node? Is every node a host?
   • A security camera sends its video to the server. Is it a host?

   Responses to expect

   • The use-or-pass-on question is answered quickly; spend the time on the camera, where many say it is not a host because nobody uses it.
   • If a learner says “for its own use” sounds like a person's account, rephrase: the data is the device's own, created or used by it.
   • Diagram guidance: hosts are drawn inside nodes because every host is also a node. The switch, access point and router are outside the inner box because, in these journeys, they only passed data along.
   • On screen in turns: the question, its answer, the two definitions, the diagram, then the camera question and its answer.

   Misconceptions to challenge

   • A learner may believe: “Hosts are the computers people use.” Respond: A host is any device with data of its own: a printer or a camera counts.
   • A learner may believe: “A switch can never be a host.” Respond: A managed switch sends and receives a little data of its own when a technician manages it. On the print job's route, it only passed data along.

   If the explanation does not land: The post: houses send and receive letters of their own (hosts); sorting offices only pass them on (nodes that are not hosts).

   In the lesson window

   • Think it through: A print job travels from a teacher’s laptop, through a wireless access point and a switch, to a printer. Which of these four devices used the print job, and which only passed it along?
   • Check your understanding: A school’s security camera records video of the car park and sends it, over the network, to the school server to be stored. Nobody sits at the camera or types on it. Is the camera a host?

9. 8. Network scope Predict 4 min

   Purpose: Name network sizes from personal to wide area, without fixed distance rules.

   Ask

   • What sizes of network lie between headphones and a company in three countries?
   • Is there a distance at which a LAN becomes a MAN?

   Responses to expect

   • A building and a city are the usual answers.
   • On screen in turns: the question, its answer, the table, then why the labels are not distances.

   Misconceptions to challenge

   • A learner may believe: “Each scope has a fixed size in metres or kilometres.” Respond: They describe scale, not distance limits. Two sites in one city might be a MAN, or part of a larger WAN.

   In the lesson window

   • Think it through: Your phone and its wireless headphones form a tiny network. A company joining its offices in three countries forms a huge one. What other sizes of network can you think of between those two?

10. 9. Networks and security Discover 8 min

    Purpose: Teach and assess the fifth objective: a connection gives a route, not permission, and connected devices bring basic risks; keeping a computer off the network removes one route, not every route.

    Ask

    • The visitor's laptop is on the school network. Can they now open the server's files? What would decide?
    • Even without opening files, what could go wrong with an unchecked laptop on the network?
    • The exam computer is never connected. How could it still be attacked?
    • Why give visitors a separate Wi-Fi network?

    Responses to expect

    • Some assume being on the network means access to everything; separate the route from the check.
    • For the risks, accept anything about harmful software, attackers getting in, data being read on the way or the wrong people joining; the reveal names four.
    • The visitors' Wi-Fi check assesses both halves of the objective: the server still checks who is asking, and separation removes the route for unchecked devices.
    • On screen in turns: the visitor question and its answer, the risks question and its answer, the exam computer and its answer, then the visitors' Wi-Fi check and its answer.

    Misconceptions to challenge

    • A learner may believe: “Anyone on the network can use everything on it.” Respond: The network gives a route; the server still decides who may use it.
    • A learner may believe: “Every cyberattack needs a network.” Respond: An infected USB drive can compromise an isolated computer.

    Discussion pause: Ask for a show of hands on the visitor question before revealing; the split is useful.

    In the lesson window

    • Think it through: A visitor plugs their own laptop into a spare network point in the wall of an empty room at the school, and the laptop joins the school network. Does that mean the visitor can now open the files on the school server?
    • Think it through: A visitor’s laptop has joined the school network through a spare network point, but it cannot open any files on the server. What could still go wrong, for the school or for the people using its network?
    • Think it through: A school keeps its exam papers on a computer that is never connected to any network, wired or wireless. Can that computer still be attacked?
    • Check your understanding: A school gives visitors their own Wi-Fi network, kept separate from the network that staff computers and the school server use. What is the main reason for keeping it separate?

11. 10. Apply it in a new situation Apply 5 min

    Purpose: Set up independent application in new situations, ideally on a later day: the four elements as a troubleshooting tool, and scope.

    Ask

    • Who will try these now, and who will come back to them later in the week?
    • For the tablet: what does the printing app share with the apps that work?

    Responses to expect

    • The tablet question tests the four elements as a way to narrow down a fault; the two offices test scope. The MAN option is the common wrong answer.
    • On screen in turns: the tablet question, its answer, the troubleshooting tip, the two-office question and its answer.

    In the lesson window

    • Apply it: A teacher’s tablet is on the school Wi-Fi. Every other app on it works, including email and the web, but the printing app cannot find the printer. Which of the four elements is most likely at fault?
    • Apply it: A fictional company joins its offices in Leeds and Madrid into one network. Someone calls the whole thing a LAN, because each office has a local network. What is the better description?

12. 11. Check your understanding Check 4 min

    Purpose: Check the lesson against the approved revision-bank questions, one at a time.

    Ask

    • Answer individually, then compare with a neighbour before anyone presses Check on the shared screen.

    Responses to expect

    • These are approved bank items with one explanation each, so a wrong choice is marked only as not the best answer. Talk through the wrong options aloud.
    • The switch-or-router question has only two options; ask the class to justify the answer, not just pick it.
    • On screen in turns: the first question, then each answer and the next question, then where to practise.

13. 12. What to remember Consolidate 3 min

    Purpose: Summarise the lesson, the key terms and the misunderstandings, and point to the lessons that come next.

    Ask

    • Without looking: what does a switch join, and what does a router join?
    • Name one host and one node that is not a host from the school map.
    • Why is being connected not the same as being allowed in?

    Responses to expect

    • Devices within a network; networks to other networks. Any endpoint or server is a host; the switch, access point or router, in these journeys, is a node that is not.
    • On screen in turns: the heading on its own as a recall prompt, the summary, the key terms, then the misunderstandings.

14. Lesson recap Closing

    On screen: the lesson’s objectives again; Next adds the closing question, which asks the class to explain each one in their own words without looking back. It says nothing about what anyone has learnt: use the answers to decide what to revisit.

    Points to listen for

    • Connected is not the same as communicating: devices need shared rules.
    • Application, protocol, network card, media: the four elements to check when something fails.
    • A network interface card connects a device by cable or by Wi-Fi; its MAC address tells it apart locally.
    • Switches and access points join devices; routers join networks.
    • Hosts have data of their own; some nodes only pass it on.
    • Network names describe scale, not distance limits.
    • A connection is a route, not permission.

Consolidation

• Connected is not the same as communicating: devices need shared rules.
• Application, protocol, network card, media: the four elements to check when something fails.
• A network interface card connects a device by cable or by Wi-Fi; its MAC address tells it apart locally.
• Switches and access points join devices; routers join networks.
• Hosts have data of their own; some nodes only pass it on.
• Network names describe scale, not distance limits.
• A connection is a route, not permission.