lesson
Make requirements observable
1 · Learn
A requirement should describe behaviour that can be checked. 'Easy to use' needs concrete tasks and criteria; 'reject a score outside 0–100' gives a clear rule. Tests should be planned before declaring implementation complete.
Separate a requirement from an implementation preference. A user may need a saved result without caring which internal storage format is chosen.
2 · Worked example
For a score form, tests include -1,0,100,101 and a non-numeric entry. These check the stated range and type rules.
3 · Your turn
What expected result should a score of 101 have under the 0–100 rule?
Check your answer
It should be rejected with a clear correction message and not saved as valid.
4 · Apply your learning
Turn three vague wishes into testable requirements for a small local quiz project.
Adult guidance and safety
Work in an approved local sandbox with invented records and test accounts. Do not access other people's systems or collect real credentials. Practical project evidence is required in addition to these explanations; this is not a specified GCSE Computer Science course.
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