SDLC Models

Lesson objectives

By the end of the week, learners should be able to:

1. Define sequential and spiral SDLC models.
2. Compare them on risk analysis, customer involvement and documentation.
3. Explain why spiral suits safety-critical systems.
4. Name one advantage and one disadvantage of each model.
5. Choose a model suited to a named scenario.

Key vocabulary

• Sequential model: a linear model progressing strictly through stages.
• Spiral model: a risk-driven model repeating planning, building and testing.
• Risk analysis: identifying potential failure points early.
• Customer involvement: keeping the user engaged throughout development.
• Advantage: a benefit offered by a particular approach.
• Disadvantage: a drawback of a particular approach.
• Safety-critical: systems whose failure harms people or property.

Common misconceptions

• "Every project uses the same model." Different projects suit different lifecycle models.
• "Spiral has no disadvantages." Spiral adds complexity and cost that sequential avoids.
• "Risk analysis means planning only." Risk analysis also feeds test and design decisions.

Teacher activities

1. Starter: display a spiral model and a waterfall model and ask which suits a medical infusion pump.
2. Define sequential and spiral models one by one.
3. Compare both on risk analysis, customer involvement and documentation.
4. Explain why spiral suits safety-critical systems.
5. Introduce the advantages and disadvantages of each model.
6. Close with the model-choice task and exit question.

Student activities

1. Choose the starter item and explain the reason.
2. Define sequential and spiral models in their own words.
3. Compare both models on risk analysis, customer involvement and documentation.
4. Explain why spiral suits safety-critical systems in one paragraph.
5. Name one advantage and one disadvantage of each model.
6. Choose the model suited to a named scenario and justify it.
7. Answer the exit question in one sentence about model choice.

Practical / learning evidence

A two-model comparison chart with advantages and disadvantages, a spiral-versus-sequential explanation and a named-scenario choice. Submit all three for marking.

Resources and preparation

Printed comparison templates, blank diagrams and sample scenarios. Offline route: paper versions, no device needed. Display models carefully and avoid recommending unsupported tools.

Assessment for learning

Inspect the comparison chart for three criteria filled correctly per model. Mark the advantages and disadvantages for accuracy. Check the named-scenario choice for a defensible rationale. Flag any learner who claims every project uses the same model.

Inclusion and homework

Provide the chart prefilled for advantages and disadvantages and allow oral scenario choice. Extend confident learners with three more models and a sixth homework choosing a model for your family car's infotainment system. Homework: name one advantage and one disadvantage of spiral and explain why not every project uses it.