AQA GCSE Computer Science (8525)Specification point 3.1.1

AQA 8525 3.1.1: Representing algorithms

The free BugBot lessons that teach this point, a robot to try it on, and the past-paper questions that test it.

What it covers

A delivery robot in a warehouse does one enormous job: collect orders and bring them to the loading bay. Nobody writes that as one enormous program. They break the job into smaller problems, and those into smaller ones, until each piece is simple. And they hide the details of each piece behind a name. Those two ideas are decomposition and abstraction, and they are how every large program is built.

• Decomposition: breaking a problem down
• Abstraction: hiding the details
• Building from the bottom up, testing as you go

Or do it in the simulator, with tasks that mark themselves

Lessons that teach it

1. F4.4 Decomposition and abstraction Functions and structured code
   Structure diagrams, and hiding the details of a job behind a function.
2. F5.1 What an algorithm is Algorithms
   Inputs, processes and outputs; what makes an algorithm precise; programs implement algorithms.
3. F5.2 Flowcharts Algorithms
   The standard symbols, and turning a flowchart into code.
4. F5.3 Pseudocode and the exam reference language Algorithms
   Reading and writing your board's pseudocode, and translating it into Python.
5. F5.4 Trace tables Algorithms
   Following an algorithm line by line, and tracing to find a logic error.

Try it on a robot

The task from F4.4 Decomposition and abstraction, running here. Change the program and press Run.

Past paper questions on this

Real exam questions that test this, each worked through with a program you can run.

• AQA 8525 June 2025 Paper 1, Question 4: Validate a name by length until it is accepted, test data, and a username flowchart 13 marks
• AQA 8525 June 2025 Paper 1, Question 7: Read a subroutine: purpose, outputs, return value, parameter 7 marks
• AQA 8525 June 2023 Paper 1, Question 5: Trace a flowchart with a loop 3 marks
• AQA 8525 June 2022 Paper 1, Question 4: Which of two programs is more efficient, and why 3 marks
• AQA 8525 June 2022 Paper 1, Question 10: Trace a REPEAT UNTIL loop with DIV, then compare it with WHILE 8 marks
• AQA 8525 Sample Paper 1, Question 13: Move blocks between columns with MOVE and HEIGHT, keeping their order 10 marks
• OCR J277 June 2025 Paper 2, Question 2(a), (b): Count the passes of a flowchart loop, and describe the kinds of iteration 8 marks
• OCR J277 June 2025 Paper 2, Question 6(d): Trace a loop that totals an array, then refine it 7 marks
• OCR J277 June 2024 Paper 2, Question 2: Complete a flowchart that decides odd or even with MOD 4 marks
• OCR J277 June 2024 Paper 2, Question 9(b): Trace an if, elseif, else algorithm that scores a javelin throw 4 marks
• OCR J277 June 2023 Paper 2, Question 1(b) to (d): An assignment, the arithmetic operators, and a do until trace table 7 marks
• OCR J277 June 2022 Paper 2, Question 2(b): Design a flowchart that decides who gets a half-price meal 5 marks

The specification is AQA's own document; this page says which of our lessons teach point 3.1.1 and is not endorsed by the board.