AQA GCSE Computer Science (8525)Specification point 3.2.11

AQA 8525 3.2.11: Robust and secure programming

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

Lessons that teach it

1. F1.4 Errors: syntax, runtime and logic Programming basics
   Reading an error message, and the three kinds of error by their exam names.
2. F6.1 Defensive design and validation Robust programs
   Anticipating misuse; presence, type, range, length, format and look-up checks.
3. F6.2 Authentication Robust programs
   Usernames and passwords, limiting attempts, and stronger ways to prove who someone is.
4. F6.3 Testing and test data Robust programs
   Iterative and final testing; normal, boundary, invalid and erroneous data; test plans in code.
5. F6.4 Debugging logic errors Robust programs
   Finding the mistake that gives no message: watching, printing, stepping and common bugs.

Try it on a robot

The task from F1.4 Errors: syntax, runtime and logic, 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 9: Which of five algorithms correctly total an array 2 marks
• AQA 8525 June 2024 Paper 1, Question 3: random.randrange, a test plan, and a syntax and a logic error 6 marks
• AQA 8525 June 2024 Paper 1, Question 11: Authenticate against two username and password pairs until valid 7 marks
• AQA 8525 June 2023 Paper 1, Question 4: Trace a Python function with three sets of inputs, then make it robust 4 marks
• AQA 8525 June 2023 Paper 1, Question 6: Fill the gaps in a login routine 4 marks
• AQA 8525 June 2023 Paper 1, Question 10: Trace nested FOR loops over a list of scores and find the error 6 marks
• AQA 8525 June 2023 Paper 1, Question 11: Normal, erroneous and boundary test data, and a logic error 5 marks
• AQA 8525 June 2023 Paper 1, Question 13: Validate a grid reference until it is correct 6 marks
• AQA 8525 June 2022 Paper 1, Question 5: A syntax error and a logic error in a random number program 5 marks
• AQA 8525 June 2022 Paper 1, Question 13.1: Keep asking until a number is between 1 and 100 4 marks
• AQA 8525 Sample Paper 1, Question 15: Fix a loop that prints odd numbers so that it works for negative input 4 marks

The specification is AQA's own document; this page says which of our lessons teach point 3.2.11 and is not endorsed by the board.