The big idea: Decomposition, pattern recognition, abstraction and algorithmic design are not a programming method.
They are how any hard problem in computer science gets made solvable — and you have already used all four in this course.
You have met them already: Normalising a database was decomposition. An ERD was abstraction. A truth table was pattern recognition.
This micro names what you were doing, so you can do it deliberately.
Free preview
This is the free notes preview
You're reading the free notes. Aimnova Pro unlocks the full study experience — and you can try it with your first topic free to keep:
- FlashcardsLock in vocabulary and key terms with spaced repetition.
- Practice questionsAnswer exam-style questions and get instant AI marking.
- Mock exams & past-paper vaultSit full mocks and see exactly how examiners award marks.
- Personalised study planA daily plan built around your exam date and weak areas.
Start Studying Free Full access to Aimnova Pro · cancel anytime
1
Database design
2
Data analysis
3
Machine learning
4
Network security
Why this matters for the exam: Paper 2 sets a question on algorithmic thinking with no code to read or write.
It is testing exactly this: can you take a problem in words and make it solvable, without reaching for a programming language.
Get feedback like a real examiner
Submit your answers and get instant feedback — what you did well, what's missing, and exactly what to write to score full marks.
Try AI Tutor FreeYour first topic is free to keep • No credit card required
A method for unfamiliar problems: When a question describes something unfamiliar, the four concepts are a procedure, not a topic.
Apply them in order and an unfamiliar problem becomes several familiar ones.
1
1 — What are the pieces?
2
2 — What repeats?
3
3 — What can I ignore?
4
4 — What are the steps?
The trace is not optional: Working a small example by hand is what turns a plausible-looking algorithm into one you know is right.
It is also, very often, exactly what the exam asks you to do.
How this is tested — you must apply the concepts to an unfamiliar problem and show the thinking, not write code. It comes up two ways:
Paper 2 — working with code
- Explain how the concepts solve a described problem, 4-6 marks
- Break an unfamiliar problem into parts
- Justify what you chose to ignore
Paper 2 — the algorithmic-thinking question
- The algorithmic-thinking question is set here deliberately
- No code to read or write — the reasoning is the answer
The classic trap: Jumping to a solution. The marks are for the route — the pieces you identified, the pattern you spotted, what you left out and why. A right answer with no reasoning scores poorly here.
IB-style questionExplain[6 marks]
A city wants to know which of its 400 bus stops should get a shelter first. Explain how computational thinking would be applied. No code is required.
Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.