2.2 Design
Design algorithms, interfaces, validation, data structures and modular program components that satisfy the scenario.
How to study WJEC GCSE Computer Science
Learn the computing principle, apply it to the named system or scenario, trace the data and control flow, and test the result against requirements.
Core concepts
Concept 1
Pseudocode, flowcharts, structure diagrams, subroutine interfaces and module relationships
Exam cue: Identify the current WJEC unit, the command word and whether the task asks for knowledge, application or computational analysis.
Concept 2
Input, output and graphical user-interface design using appropriate controls and feedback
Exam cue: Link every design element to a requirement, specify data movement and edge cases, and make module inputs, outputs and responsibilities explicit.
Concept 3
Data types and structures, file design, validation, verification, authentication and processing rules
Exam cue: Use precise terminology, trace inputs and state changes, and test the answer against the data, scenario or program behaviour.
Risk pitfalls and guardrails
Producing attractive interface sketches without specifying algorithms, data structures, validation, state changes or module interaction.
Guardrail: Avoid generic descriptions, unchecked traces and cross-board assumptions; make every answer depend on the named data, system, algorithm or scenario.
Importing the legacy WJEC structure, a different board's content or a Foundation/Higher tier assumption.
Guardrail: Use qualification code 3460QS or 3460CS and the current two-unit untiered structure; do not import a legacy or cross-board route.
Giving a generic description without applying it to the named system, data set, algorithm or pre-release scenario.
Guardrail: Practice cannot replace the annual live brief, specified Python environment, clean-copy rule, restricted examination files or Surpass upload process.
Memory anchors
Structure diagram
A hierarchical representation of a solution divided into modules or subroutines.
Interface
The agreed inputs, outputs and interaction through which components or users communicate.
Data model
A structured representation of the data, relationships and rules needed by the solution.
Validation rule
A test of whether input is plausible, such as range, type, length, format or presence.
Authentication design
A planned method for checking identity and controlling access without exposing sensitive credentials.
Usability
How effectively, efficiently and comfortably intended users can complete their tasks.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
What should a design do before Python is written?
Why use pseudocode for a program design?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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