07 · Foundations

Scrum

Scrum is a lightweight framework for delivering work in fixed-length iterations, with explicit feedback loops at the start, daily, and end of each iteration. It is a framework, not a methodology — it tells you the events and roles, not how to engineer.

The three roles

• Product Owner — owns the backlog. Decides what and in what order. One person, not a committee.
• Scrum Master — owns the process. Removes impediments, coaches the team on Scrum. Not a project manager.
• Developers — own the how. Self-organising, cross-functional. Three to nine people.

The five events

• Sprint — the container. Fixed length (commonly 2 weeks). Goal, scope, and team are stable inside it.
• Sprint Planning (start) — the team picks items from the backlog they can complete this sprint. Output: a Sprint Goal and a Sprint Backlog.
• Daily Scrum / Standup — 15 min, every day. Three questions: what did I do, what will I do, what's blocking me. Not a status report to the boss — a synchronisation between developers.
• Sprint Review (end) — demo the increment to stakeholders. Adjust the backlog based on feedback.
• Sprint Retrospective (end) — inspect how the team worked, not what they built. One or two actionable improvements.

The three artifacts

• Product Backlog — the ordered list of everything that might be done. Owned by the PO. Lives forever.
• Sprint Backlog — what the team committed to this sprint plus the plan to deliver it. Lives for one sprint.
• Increment — the working, integrated software produced this sprint. Must meet the Definition of Done.

Definition of Done

The agreed checklist that turns "we wrote some code" into "we shipped a feature":

• Code reviewed and merged.
• Tests green; coverage above the floor.
• Documentation updated.
• Deployed to staging (or beyond).
• Acceptance criteria from the story are met.

Estimation

Story points are a relative size, not a duration. A 5 is bigger than a 3 and smaller than an 8 — that's all. Velocity (points completed per sprint) emerges from doing the work; it is a measurement, not a target. Goodhart's law applies: the moment you optimise for velocity, it stops being useful.

Common anti-patterns

• Scrumfall — Waterfall phases inside the sprint (3 days of design, 4 of code, 2 of test). Defeats the point.
• Scrum master as project manager — chases deadlines and assigns tasks. They should remove impediments, not micromanage.
• Daily as status meeting — developers report to the manager. Stops being a synchronisation; becomes theatre.
• Cargo cult — running the events without the principles. Holding a retrospective and ignoring its output.

Scrum exposes problems. It doesn't solve them. If the team's retros generate the same three complaints sprint after sprint, the framework is working and the team is not listening.

What to remember at exam time

• 3 roles, 5 events, 3 artifacts.
• Sprint length is fixed and never extended to "fit one more story".
• The Daily is for developers, not the PO or manager.
• Definition of Done is set by the team and applies to every item.
• Story points are relative, not hours.