Three teams, one canteen app
Your college wants an app to order lunch from the canteen. Three teams want the job.
Team one plans every screen for three months, then builds it. Team two makes a rough version in one week, lets students try it, and improves it. Team three builds only the order button first, because that is what students really need.
Software teams use all three ideas. The first is Waterfall (fixed steps). The second is RAD (building rough early versions fast). The third is Lean (no waste). Which team would you pick?
Key words
| Word | What it means | Example |
|---|---|---|
| Waterfall | A way of working in fixed steps. You finish one step before the next. | plan, design, build, test, release |
| Artefact | A document or other thing a project makes. | a requirements document |
| RAD | Rapid Application Development: build quick prototypes and improve them. | a rough clickable screen in week 1 |
| Prototype | An early, simple version that you can try. | a clickable drawing of the screens |
| Reuse | Using code or parts that already exist. | the same login box in every app |
| Lean | A way of working that cuts waste and builds only what is needed. | no unused features |
| Waste | Work that adds no value. | a feature that nobody uses |
| Return on investment | The value you get back for the money you spend. | money earned after the app is built |
| Requirement | Something the software must do or be. | pay by card |
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Quick check: Waterfall
Have a go
Quick check: Waterfall
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Key features of Waterfall
| Feature | What it means | Good or bad? |
|---|---|---|
| Fixed, ordered steps | You finish one step before you start the next | Clear plan, but hard to change |
| Progress is counted in artefacts | You measure documents and parts completed | Easy to report |
| High cost at the start | A lot of money is spent before anything works | Slow return on investment |
| Cancelled early, nothing to use | Little or no working code exists | Risky |
| Little client contact | The client talks mostly at the start and the end | Misunderstandings are found late |
| A lot of documentation | Everything is written down | Good for rules and safety, slow |
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RAD: build, show, improve
RAD means Rapid Application Development. The team builds a rough prototype very fast, shows it, and improves it again and again.
It reuses code that already exists. It aims to build all the features first, and to make them good later. Early on, the client may see only a mock-up (a drawing of the product). RAD suits small and medium projects.
Lean: cut the waste
Lean thinks about waste. Waste is any work that adds no value to the user.
Lean makes decisions as late as possible, so less work is thrown away. It uses short rounds and delivers a version that is good enough to use, not every feature. It suits small teams with few resources.
Compare Waterfall, RAD and Lean
| Question | Waterfall | RAD | Lean |
|---|---|---|---|
| Main idea | Fixed steps, one after another | Quick prototypes, improved again and again | Cut waste, build only what is needed |
| Does the client see working software early? | No | Maybe a mock-up | Yes, in short rounds |
| Documentation | A lot | Light to medium | Light |
| Best for | Fixed, clear requirements | Small to medium projects, quick start | Small teams, few resources |
| Main risk | Mistakes are found late | Quality comes second | Decisions left too late |
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