Computational Thinking Exam Practice (OCR J277 Paper 2 Style)

This lesson consolidates everything from OCR J277 Section 2.1 with exam-style practice and techniques for tackling computational thinking questions in Paper 2.

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Key Topics Checklist

Topic	Key Points
Computational thinking	Four components: decomposition, abstraction, algorithmic thinking, pattern recognition
Decomposition	Breaking problems into manageable sub-problems; leads to subprograms
Abstraction	Removing unnecessary detail; focusing on relevant information
Algorithmic thinking	Step-by-step solutions; sequence, selection, iteration
Pattern recognition	Identifying similarities; generalisation; code reuse
Inputs, processes, outputs	IPO model; identify all three for any system
Structure diagrams	Visual representation of decomposition; hierarchical tree
Flowcharts	Standard symbols; terminators, processes, decisions, I/O
Pseudocode	OCR reference language; variables, selection, iteration, arrays, functions

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How Computational Thinking Is Tested in OCR J277 Paper 2

Paper 2 (Computational Thinking, Algorithms and Programming) tests Section 2.1 through:

Identification questions (1-2 marks)

• "Identify the inputs and outputs for this system." (2 marks)
• "Name two components of computational thinking." (2 marks)

Application questions (2-4 marks)

• "Decompose the following problem into sub-problems." (3 marks)
• "Draw a structure diagram for this system." (4 marks)

Design questions (4-6 marks)

• "Draw a flowchart to show this algorithm." (5 marks)
• "Write pseudocode to solve this problem." (6 marks)

Trace and analysis questions (3-6 marks)

• "Complete the trace table for this algorithm." (4 marks)
• "State the output of this algorithm when the input is 7." (2 marks)

OCR Exam Tip: Paper 2 questions are more practical than Paper 1. You will need to actually design algorithms (pseudocode and flowcharts), trace through code, and apply computational thinking to given scenarios. Practice is essential.

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Worked Example 1: Decomposition and Abstraction

Question: A school wants to create a system to manage student homework. (a) Decompose this problem into at least four sub-problems. (4 marks) (b) Explain how abstraction would be used when designing the student record for this system. (2 marks)

Model answer (a):

1. Setting homework (teacher enters homework details: title, description, due date, class). (1)
2. Distributing homework (system sends homework to students in the selected class). (1)
3. Submitting homework (student uploads or enters their completed work before the deadline). (1)
4. Marking homework (teacher reviews submissions and assigns marks/grades). (1)
5. Tracking completion (system records who has and has not submitted). (1)

Any four valid sub-problems for 4 marks.

Model answer (b): Abstraction would be used to include only the relevant data about each student, such as their name, student ID, and class group (1). Unnecessary details like their height, eye colour, or home address would be excluded because they are not relevant to the homework management system (1).

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Worked Example 2: Flowchart

Question: A cinema charges different ticket prices based on age. Under 12: £5. 12-17: £7. 18 and over: £10. Draw a flowchart that inputs a customer's age and outputs the correct ticket price. (5 marks)

Model answer:

[Start]
   |
[INPUT age]
   |
<Is age < 12?> --Yes--> [OUTPUT "£5"] --> [Stop]
   |
  No
   |
<Is age < 18?> --Yes--> [OUTPUT "£7"] --> [Stop]
   |
  No
   |
[OUTPUT "£10"]
   |
[Stop]

Marking points:

• Correct use of terminator symbols (Start/Stop) (1)
• Correct input symbol for age (1)
• Correct decision symbols with Yes/No labels (1)
• Correct output symbols for each price (1)
• Correct logic — all ages produce the right output (1)

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Worked Example 3: Pseudocode and Trace Table

Question: Study the following pseudocode: