Fiducia TogetherDecomposition and abstraction
Breaking a problem into parts, and ignoring the detail that does not matter.
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.
What it is
Decomposition breaks a large problem into smaller sub-problems that can be solved separately. Abstraction removes unnecessary detail so the essential structure is visible. Pattern recognition spots similarities between problems.
Where it applies
GCSE and A Level computer science; together these are usually called computational thinking.
How it works
A subprogram is decomposition in code: a named block doing one job, callable from elsewhere. That gives reuse, readability and easier testing.
Abstraction is why a map is useful — it leaves out almost everything.
How to use it in your work
For "explain how decomposition would help" questions, name the specific sub-problems for the scenario given. A generic answer scores little.
For abstraction, say what is removed AND why removing it is safe.
Where to get help
Your teacher and your board's specification — the pseudocode and the required language differ between boards. Bitesize covers the concepts; the computer science song runs the topics.
Revise this with a song
These are ours. We write revision songs because a lot of people remember a tune when they cannot remember a page, and because revising out loud in the kitchen beats staring at a highlighter.
- The Computer Science Song The GCSE computer science topics, set to music.
Where to read more
Last reviewed 2026-08-28 by Fiducia Together · Next review due 2027-08-28
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.