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Computing · JC 1

Active learning ideas

Web Application Architecture and Security

Active learning works for this topic because students need to see how abstract identifiers like IP addresses and domain names function in real network communication. When they simulate DNS resolution or trace IP commands, they move beyond memorization to grasp the practical mechanics of internet routing.

MOE Syllabus Outcomes9569 5.3.1 Describe client-server architecture9569 5.3.2 Identify common web vulnerabilities and security measures
25–40 minPairs → Whole Class4 activities

Activity 01

Plan-Do-Review35 min · Small Groups

Role-Play: DNS Resolution Chain

Divide class into roles: user, local DNS, root server, TLD server, authoritative server. User requests a domain; servers pass queries hierarchically and return mock IP. Groups rotate roles for three domains, noting delays at each step. Debrief on hierarchy benefits.

How does the client-server model function in web applications?

Facilitation TipDuring the DNS Resolution Chain, assign each student a distinct role (user, DNS resolver, root server) and provide props like sticky notes to represent packets for clear visual tracking.

What to look forPresent students with a list of IP addresses (e.g., 172.217.160.142) and domain names (e.g., www.google.com). Ask them to write down which is which and briefly explain the role of DNS in connecting the two.

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Activity 02

Plan-Do-Review25 min · Pairs

Command-Line: IP Lookup Lab

Pairs access school computers to run 'nslookup' or 'ping' on sites like google.com.sg and record IP-domain pairs. Compare IPv4 vs IPv6 results. Chart findings and discuss dynamic vs static IPs using 'ipconfig'.

What are common web security threats like SQL injection and XSS?

Facilitation TipFor the IP Lookup Lab, pre-configure laptops to show both successful and failed ping attempts, so students observe timeouts and dynamic IP shifts after router resets.

What to look forPose the question: 'Imagine the DNS system suddenly stopped working globally. Describe two specific problems you would immediately encounter when trying to use the internet, and explain why these problems would occur.'

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Activity 03

Concept Mapping40 min · Small Groups

Concept Mapping: Classroom Network Diagram

Small groups scan local Wi-Fi devices with tools like Angry IP Scanner, list IPs and resolve domains. Draw network map on chart paper, labeling gateways. Share maps to identify patterns like subnet ranges.

How can encryption and authentication secure web data?

Facilitation TipWhen creating the Classroom Network Diagram, give groups a mix of IPv4 and IPv6 addresses to include, ensuring they label both node types and connection types accurately.

What to look forOn an index card, ask students to write down one difference between IPv4 and IPv6 addresses and one reason why the DNS system is structured hierarchically.

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Activity 04

Formal Debate30 min · Whole Class

Formal Debate: No DNS Scenario

Whole class splits into teams to argue impacts of memorizing IPs instead of domains: list pros, cons, real-world effects. Vote and summarize key risks like errors in routing.

How does the client-server model function in web applications?

Facilitation TipIn the No DNS Scenario debate, provide a short scenario script to ground the discussion, then time responses strictly to keep arguments concise and evidence-based.

What to look forPresent students with a list of IP addresses (e.g., 172.217.160.142) and domain names (e.g., www.google.com). Ask them to write down which is which and briefly explain the role of DNS in connecting the two.

AnalyzeEvaluateCreateSelf-ManagementDecision-Making
Generate Complete Lesson

A few notes on teaching this unit

Teachers should start with concrete, relatable examples—like comparing IP addresses to Singapore postal codes—before introducing abstractions. Avoid overwhelming students with binary or hexadecimal math; instead, emphasize patterns in dotted decimal and colon-separated formats. Research shows that hands-on simulations outperform lectures for network concepts, so prioritize role-plays and command-line tools over slides.

Successful learning looks like students confidently distinguishing IPv4 from IPv6, explaining why domain names exist, and tracing how a DNS request translates to an IP address. They should also recognize dynamic IP changes and the distributed nature of DNS through concrete examples.


Watch Out for These Misconceptions

  • During the IP Lookup Lab, watch for students assuming their device’s IP remains unchanged after a router restart. Redirect by having them document the new IP they receive from the DHCP server and compare it to the old one.

    Use the ping command before and after restarting the router, then have pairs compare results. Ask them to note the lease time displayed in their router settings to explain why IPs change.

  • During the DNS Resolution Chain role-play, watch for students thinking domain names are the actual addresses used by devices. Redirect by having the final 'device' only accept the numeric IP as valid, forcing students to translate the name first.

    After the role-play, ask the class to identify which step performed the translation and why the device couldn’t use the name directly. Emphasize the output from the authoritative DNS server in their scripts.

  • During the Classroom Network Diagram activity, watch for students drawing a single central DNS server. Redirect by having groups trace a query through multiple levels (root, TLD, authoritative) using colored arrows to show delegation.

    Provide a starter diagram with labeled layers but blank spaces for server roles. Require students to fill in at least three levels and explain how each handles part of the request.


Methods used in this brief