Network Protocols Basics

Overview

In this lesson (Lesson 4 of 8), students build on earlier ideas about how data moves through networks by learning the purpose of key protocols. They investigate how TCP/IP helps devices communicate reliably and how HTTP enables web data transfer, including why this matters for security and integrity.

Learning intentions

• Students will describe how network protocols support data transmission across wired and wireless networks.
• Students will explain the role of TCP/IP in breaking data into packets, delivering them, and confirming receipt.
• Students will explain the role of HTTP in requesting and sending web data.
• Students will investigate simple indicators of communication problems and suggest solutions.

Success criteria

• I can explain, in my own words, what a protocol is and why networks need them.
• I can describe how TCP supports reliable delivery using acknowledgements.
• I can identify how HTTP is used to request and retrieve web content.
• I can link network communication issues (like dropped packets) to possible outcomes and fixes.

Curriculum links

• AC9TDI8K02: describe how data transmission works in wired and wireless networks including the internet, using properties such as reliability, latency and how issues occur.
• AC9TDI8K02: investigate how data is transmitted and secured in wired and wireless networks including the internet, focusing on why integrity matters during transfer.
• AC9TDI8E3: explore simple encryption and decryption algorithms (as a preview for later lessons on securing data during transmission).
• General capability: critical and creative thinking through investigating “what happens when packets don’t arrive?” scenarios.

Lesson structure (60 minutes)

1. 0–7 min · Hook (Protocol detectives). Teacher displays two short “messages” written as if sent without rules (e.g., “send request now” vs “GET /cat.png HTTP/1.1”). Students quick-write: what would be unclear for the receiver and what rules would be needed.

2. 7–15 min · Direct teach (What protocols do). Teacher explains that protocols are shared rules for communication, then introduces the internet as a “network of networks” using TCP/IP and web traffic using HTTP. Students annotate a class summary: sender, receiver, packets, and “confirm delivery” ideas.

3. 15–30 min · Guided investigation (TCP vs unreliable delivery). Teacher runs a rapid simulation with the class in pairs (using scenario cards and a “packet tray”).

• Step A: Pairs “send” numbered packets of a sentence to another pair. Sometimes the teacher removes one packet to simulate dropping.
• Step B: Repeat, but now the receiver must acknowledge which packet numbers they got, and the sender resends any missing packets (TCP-style idea). Students record outcomes: time taken, missing data, and how acknowledgements change reliability.

4. 30–40 min · Protocol focus (TCP/IP and HTTP roles). Teacher explains:

• TCP/IP: supports reliable communication and routing between devices; TCP uses acknowledgements to confirm packets have been received.
• HTTP: defines how web requests are made and responses are returned (request/response model). Students complete a quick “role matching” task: Students match protocol to function (e.g., “confirm packets received” → TCP; “GET a webpage/resource” → HTTP).

5. 40–52 min · Data integrity mini-check (Why correctness matters). Teacher introduces the idea of integrity as “the data arriving is the right data”. Without deep cryptography yet, students consider simple checks: if one character in a message is wrong, the receiver may reject or correct. Teacher links this to later security work. Students practise with a short worksheet: they are given a message with one altered character and decide whether it “makes sense” to accept or whether it needs retransmission/verification.

6. 52–58 min · Whole-class discussion (Problem → solution). Teacher prompts: “If packets are dropped or delayed, what changes in user experience (loading slowly, broken images, repeated attempts)?” Students suggest solutions in general terms (retry, acknowledgement, improved reliability). Teacher captures answers on the board.

7. 58–60 min · Exit ticket (1 minute check + 1 application). Students answer two prompts:

• Define protocol in one sentence.
• Explain one difference between TCP-style reliable delivery and unreliable sending (no acknowledgements).

Resources

• Protocol definition cards (protocol, packet, acknowledgement, request/response)
• Packet simulation cards with numbered “packets” and a sentence to transmit
• “Packet tray” container or folder system for each group
• Role matching worksheet (TCP/IP vs HTTP)
• Short integrity mini-worksheet (messages with one incorrect character)
• Exit ticket slips or a shared form template (no internet required)
• Board/slide with a simple diagram: sender → packets → receiver → acknowledgement → resend/missing fix

Assessment

• Observation during the packet simulation: students’ ability to use acknowledgements to reason about missing packets.
• Role matching worksheet: identifies correct understanding of TCP/IP and HTTP purposes.
• Exit ticket: checks definitions and the reliable-vs-unreliable comparison aligned to network communication concepts.

Differentiation

• Support: provide sentence starters for protocol explanations (“A protocol is…”, “TCP helps by…”, “HTTP is used when…”).
• Support: during simulation, assign clear roles (sender, receiver, recorder) and provide a simple recording template.
• Extension: students choose a “real-world symptom” (slow page load, missing image, repeated loading) and write a likely cause linked to dropped packets or delivery delays.
• EAL/SEN: use visual cues (arrows, icons for request/response, checkmarks for acknowledgements) and allow oral responses to be recorded by a peer or teacher.