Edexcel IGCSE Computer Science: Frequent mistakes

Pearson Edexcel Principal Examiner Feedback for IGCSE Computer Science identifies recurring errors in coding, written responses and exam technique. Avoiding these can improve your grade.

Coding and programming errors

Variable inconsistencies

Failing to maintain consistent variable capitalisation or initialisation throughout code. Changing variable names mid-program or not initialising before use.

Fix: Define variables at the start. Use same name and casing throughout. Initialise before first use.

Missing syntax elements

Forgetting colons, semicolons or other syntax required by the chosen programming language. Incomplete or invalid code.

Fix: Know your language syntax. Python: colons after IF, FOR, DEF. Check brackets, indentation.

Incomplete variable definitions

Deleting or failing to properly initialise required variables. Variables used before assignment.

Fix: Declare and initialise all variables. Check the question for required variables.

Written response errors

Imprecise terminology

Confusing related concepts:

• “Protection from malware” vs. “protection from hacking”—malware = malicious software (viruses, etc.); hacking = unauthorised access
• Describing purposes rather than definitions when definitions are asked

Fix: Define precisely. Malware = software designed to harm. Hacking = gaining unauthorised access. Use correct technical terms.

Insufficient specificity

Vague answers without enough detail. E.g. stating “filter software” without explaining what content it filters (websites, emails, etc.).

Fix: Be specific. “Content filter software blocks access to certain websites.” Not just “filter software.”

Incorrect focus

Answering tangential aspects rather than what is explicitly asked. Not focusing on the question stem.

Fix: Underline key words. Answer that aspect. Don’t go off-topic.

Reading comprehension

Not carefully reading what information is already provided in questions. Leading to redundant or irrelevant responses.

Fix: Read the question. Don’t repeat given information. Build on it.

General exam technique

Time management

Running out of time; failing to complete the paper. Paper 2 (practical) and written papers both need allocated time.

Fix: Allocate time by marks. Leave time for longer questions. Practise under timed conditions.

Over-answering short questions

Including unnecessary linked strands in 2–3 mark questions. Fewer, precise points can achieve full marks.

Fix: 2 marks = 2 clear points. Quality over quantity. Don’t overwrite.

Key examiner emphasis

Examiners emphasise:

• Precise technical terminology
• Reading questions carefully to understand exactly what is asked
• Consistency in code implementations

How Tutopiya helps

Tutopiya supports Edexcel IGCSE Computer Science. Explore IGCSE resources or book a free trial.

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Based on Pearson Edexcel IGCSE Computer Science Principal Examiner Feedback. Check Pearson website for latest specification and reports.