lesson
Related fields belong to one record
1 · Learn
A record groups related fields, such as an item identifier, title and quantity. A list of records represents several items. Choosing suitable types and stable identifiers helps prevent accidental confusion between display text and identity.
Two people or products can share a name. A name is therefore not automatically a safe unique key, and changing a display name should not create a new identity.
2 · Worked example
Items with IDs 101 and 102 can both be called 'Notebook' while remaining distinct records.
3 · Your turn
Why should a system not assume a person's display name uniquely identifies their account?
Check your answer
Different people can share a name, and names can change.
4 · Apply your learning
Create an invented record schema and explain the purpose and type of each field.
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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Check a calculation · Year 5 onward
Use this only when your teacher or adult allows a calculator for the task. Show your thinking first. It does not replace mental or written arithmetic and does not mark your lesson answer.
Powers, roots and trigonometry · Year 7 onward
Use only when the task allows a calculator. Choose one operation at a time and record your working. Trigonometry here always uses degrees (DEG), not radians. Inverse sine, cosine and tangent return an angle, not a reciprocal. Keep exact fractions and π in answers when requested.
Approximate numerical results use up to 12 significant digits. Inverse sine returns −90° to 90°, inverse cosine 0° to 180°, and inverse tangent −90° to 90°; these are principal values, not every possible solution of a trigonometric equation.
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