Planning and Design
Requirements come first
Planning and design questions punish solution-first thinking. The sequence is: elicit requirements, define scope, state objectives, identify constraints and assumptions, assess risk, then design. If an option jumps to a tool or solution before requirements are established, it is almost always wrong regardless of how sensible the solution sounds.
Concepts you must hold
- Requirement types: functional (what it must do) versus non-functional (performance, usability, accessibility, security, maintainability). Non-functional requirements are frequently forgotten and frequently tested.
- Scope and boundaries: what is explicitly in and out; the difference between scope change (controlled) and scope creep (uncontrolled).
- Objectives: specific, measurable, achievable, relevant, time-bound; stated as outcomes rather than activities.
- Constraints versus requirements: a constraint limits how you may satisfy a requirement; it is not itself a requirement.
- Traceability: every design decision should link back to a requirement, and every requirement to an acceptance criterion.
- Risk and assumptions: a risk register with likelihood and impact; an assumptions log that is actively reviewed.
- Trade-offs: time, cost, quality, and risk are balanced explicitly, with the decision and rationale recorded.
Traps
Treating a constraint as a requirement. Writing objectives that describe activity ("deliver training") rather than result. Confusing a plan with a schedule - the schedule is one component. Failing to define acceptance criteria, so "done" becomes subjective. Accepting vague requirements such as "must be accessible" without a measurable criterion.
Rule of thumb
If a design decision cannot be traced to a requirement, it is a preference - and preferences must be negotiated, documented, and prioritised, not silently adopted.
Worked example
A stakeholder states the system "must be accessible". That is not testable. Convert it into an acceptance criterion that names a standard, a scope, and a verification method, then record who confirmed it and when.