Unit 1 exam technique: the WCP01 paper

The paper

• WCP01: Principles of Computer Science. 1 hour 30 minutes, 80 marks, worth 50% of the International AS and 25% of the International A level.
• Available in January and June, as a written paper or onscreen. The first Unit 1 exam is in June 2027.
• All questions are compulsory. Question types: multiple choice, short and medium open response, extended open response, and tabular and diagrammatic items (complete a table, flowchart or diagram).
• Calculators are not allowed. Practise binary, hexadecimal and unit calculations by hand, and leave answers as expressions where a question allows (for example (5 x 2²⁰ x 8) / (20 x 10⁶)).
• In the sample assessment, sections cover networks and encryption, data structuring, data representation, enabling technologies, problem solving and computer systems; code is Python, not pseudocode.

Command words

• Give / State: a short answer, no explanation needed.
• Define: the precise meaning of a term.
• Describe: say what something is or how it works, in steps or features.
• Explain: give a reason or a cause and its effect: '... because ...' or '... so that ...'. One mark is usually for the point and one for the expansion.
• Outline: the main points briefly.
• Convert / Calculate: show your working; method marks are available even when the final answer is wrong.
• Complete: fill in the table, flowchart or diagram exactly as asked.
• Construct: build, for example, a Boolean expression.
• Trace: follow an algorithm and record values in a trace table.

Picking up marks

• Use technical terms precisely: 'MAR', 'address bus', 'two's complement', 'referential integrity', not vague words.
• Match the number of points to the marks: a 2-mark 'explain' needs a point and its expansion; a 4-mark question usually needs 4 distinct points.
• For binary arithmetic, write the carries; for conversions, show the place values.
• For trace tables, add a new row only when a value changes and read every line of the code, including loop conditions.
• In 'choose two' multiple-choice items, mark exactly two boxes.
• Spend roughly one minute per mark and leave a few minutes to check conversions.

Worked example

A 2-mark question asks: 'Explain one benefit of serial transmission over parallel transmission.' Write a full-mark answer.

1. Point: serial transmission does not suffer from skew.
2. Expansion: because bits travel one after another on a single line, they cannot arrive out of step, so data stays reliable over long distances.

Answer: No skew (1), because bits are sent one at a time on one line so they cannot arrive out of step, making it reliable over long distances (1).

Check yourself

1. The Unit 1 paper has 80 marks and lasts 90 minutes. About how many minutes are available per mark (to 2 decimal places)?
   Show answer

   1.13. 90 / 80 = 1.125, so about 1.13 minutes per mark.

2. Unit 1 is worth what percentage of the full International A level?
   Show answer

   25 %. Unit 1 is 50% of the IAS and 25% of the IAL.

3. Which equipment is not allowed in the Unit 1 examination?
   • A pen
   • A pencil for diagrams
   • A ruler
   • A calculator
   Show answer

   A calculator. The specification states calculators must not be used.

4. In a 2-mark 'explain' question, what is usually needed?
   • A point and an expansion giving the reason or effect
   • A single word
   • A list of four unrelated terms
   • A diagram only
   Show answer

   A point and an expansion giving the reason or effect. Explain needs a justification: point plus reason.

5. In the Pearson sample assessment for Unit 1, how are algorithms written in code?
   • In a made-up pseudocode only
   • In assembly language
   • In Python
   • In SQL only
   Show answer

   In Python. The qualification uses Python 3, and the sample paper's code is Python.

6. Why should you show working in a conversion question even if you are confident of the answer?
   • Method marks can be awarded even if the final answer is wrong
   • Working is never marked
   • It makes the answer longer, which earns more marks
   • The examiner needs it to read your handwriting
   Show answer

   Method marks can be awarded even if the final answer is wrong. A small slip loses only the accuracy mark if the method is shown.

Practise with instant feedback Print this lesson

Sources

• Pearson Edexcel International Advanced Subsidiary/Advanced Level in Computer Science specification (2026)
• Pearson Edexcel IAL Computer Science IAS sample assessment materials (Unit 1, WCP01)
• Pearson qualifications: International Advanced Levels Computer Science (2026)

Last updated 8 November 2026. Spotted a mistake? Tell us.