Algorithm design and problem-solving

Worked examples (6)

• 1Name the four stages (2 marks)
• 2Purpose of the design stage (2 marks)
• 3Three design tools (3 marks)
• 4Match activities to stages (4 marks)
• 5Iterative refinement and feedback (5 marks)
• 6Describe all four stages and their purpose (8 marks)

Model answers (6)

• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style

Worked examples (6)

• 1Distinguish validation and verification (2 marks)
• 2Name the validation check (2 marks)
• 3Choose and describe validation checks (8 marks)
• 4Describe verification methods (4 marks)
• 5Write a range-check validation routine in pseudocode (6 marks)
• 6Username: length check + presence, re-prompt (8 marks)

Model answers (6)

• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style

Worked examples (6)

• 1Name the four elements of computational thinking (2 marks)
• 2Identify input / process / output (2 marks)
• 3Decomposition vs abstraction (4 marks)
• 4Read a structure diagram (6 marks)
• 5Decompose a banking app (8 marks)
• 6Decompose into inputs, processes, outputs, storage (8 marks)

Model answers (6)

• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style

Worked examples (6)

• 1Identify flowchart symbols (4 marks)
• 2Identify inputs, processes and outputs (3 marks)
• 3Pseudocode for finding an average (6 marks)
• 4Complete a trace table (6 marks)
• 5Find the largest of N numbers (7 marks)
• 6Count and total with a sentinel + validation (8 marks)

Model answers (6)

• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style

Worked examples (6)

• 1Syntax vs logic errors (4 marks)
• 2Normal, abnormal and boundary data for a range (3 marks)
• 3Identify the four test-data types (8 marks)
• 4What is a run-time error? (4 marks)
• 5Trace-table dry run of a loop (6 marks)
• 6Trace a validation routine + choose test data (6 marks)

Model answers (6)

• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style

Worked examples (6)

• 1Getting started: spot u0026 fix one error (2 marks)
• 2Getting started: correct a wrong condition (2 marks)
• 3Building confidence: count items meeting a condition (6 marks)
• 4Building confidence: find the maximum of N numbers (8 marks)
• 5Stretch: identify and correct three errors (6 marks)
• 6Stretch: write u0026 refine a linear search with a flag (8 marks)

Model answers (6)

• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style
• ✓Model answer — 0478 Paper 2 — style