AQA 8525 · Section 3.1 · 3.1.1a

Computational
Thinking

Decomposition · Abstraction · Algorithmic Thinking · Pattern Recognition

CSZone AQA GCSE Computer Science 8525

Learning Objectives

By the end of this lesson you will be able to...

Define computational thinking and state its four key components

Explain decomposition and abstraction with real-world examples

Describe algorithmic thinking and pattern recognition

Apply computational thinking to solve a given problem in an exam question

Core Concept

What is Computational Thinking?

"A set of problem-solving skills that allow us to formulate problems and solutions in a way that a computer could execute."

🔨

DECOMPOSITION

Break into smaller parts

🎭

ABSTRACTION

Remove unnecessary detail

🔍

PATTERN REC.

Spot similarities

📋

ALGORITHMIC

Step-by-step solution

Decomposition

Breaking Problems Into Smaller Parts

DEFINITION

Breaking a complex problem down into smaller, more manageable sub-problems that are easier to understand and solve.

🎮 EXAMPLE — MAKE A GAME

Design the graphics

Write the game logic

Handle user input

Implement scoring

✅ WHY IT HELPS

Each part can be solved independently

Team members can work in parallel

Easier to test individual components

Problems become less overwhelming

Abstraction

Removing Unnecessary Detail

DEFINITION

Focusing on the important information only, and ignoring irrelevant details that don't affect the solution.

🗺️ TUBE MAP EXAMPLE

The London Underground map is abstracted — it shows which stations connect, but ignores the actual distances and curves of the real tunnels. Only the useful information is shown.

💻 IN PROGRAMMING

When modelling a student, we include: name, age, grade. We don't include: hair colour, shoe size. These details are irrelevant to the task.

⚡ Exam Tip:Abstraction is about identifying WHAT to include, not just what to remove.

Pattern Recognition & Algorithmic Thinking

The Remaining Two Components

🔍 PATTERN RECOGNITION

Identifying similarities, trends, or repeated elements within or between problems.

Example: Recognising that sorting a list of names uses the same algorithm as sorting a list of numbers.

📋 ALGORITHMIC THINKING

Developing a precise, step-by-step solution that a computer could follow to solve the problem.

Example: Writing the exact steps to find the largest number in a list.

Pattern recognition allows you to reuse solutions — if you've solved a similar problem before, you can apply the same algorithm rather than starting from scratch.

Exam Practice

Have a go at this question

AQA-style question

A student is writing a program to manage a school library. Describe how decomposition could be used to help design this program. Give three sub-problems they might identify.

3 marks

MARK SCHEME

1 mark each

Any three from: searching for a book · adding/removing books · managing loans/returns · checking overdue items · managing student records

Key Takeaways

What to Remember

Decomposition — break a problem into smaller sub-problems

Abstraction — remove irrelevant details; focus on what matters

Pattern Recognition — identify similarities between problems/solutions

Algorithmic Thinking — develop a precise, step-by-step solution

AQA 8525 · 3.1.1a · CSZone.co.uk