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J277 2 Paper 2 diagnostic and misconception clinic

Part 5 of 5 · J277 Paper 2 · Exam transition

Five clinics on the Paper 2 errors that repeatedly cost marks, each one diagnosed and then applied.

Students will:

  • distinguish validation from test data
  • use elements, indexes, return and print correctly
  • write condition-controlled iteration that stops when it should
  • separate searching, Boolean logic and program errors
  • describe translators and IDE facilities precisely

Inside: 7 explanation cells, 1 runnable Python task, 3 multiple-choice questions, 1 fill-in-the-blanks cell and 5 written answers. 22 marks, about 45 minutes.

Series: J277 Paper 2 · Exam transition, part 5 of 5.

Shared by Coding PathwayVerified teacher

  • 17 cells
  • About 45 minutes
  • CC BY-SA 4.0
  • Shared 17 Aug 2026
  • Updated 9 Sept 2026

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The whole resource, exactly as a class sees it. Answers and marking are held back.

Paper 2 diagnostic and misconception clinic

This final worksheet targets errors that repeatedly cost marks: imprecise definitions, confused pairs of ideas, missed boundaries and code that works only for the shown example.

Each clinic begins with a brief reminder and then asks you to apply it. If the reminder corrects something you previously believed, write a short note beginning, “I must remember that…”. The aim is diagnosis and repair, not simply collecting a total mark.

Clinic 1: validation and test data

Validation checks whether data follows chosen rules. It does not prove the data is true. Test classifications describe the purpose of a test value, and the labels can overlap: a boundary value can also be a normal accepted value.

Fill in the blanks4 marks
A program accepts whole-number ratings from 1 to 5 inclusive. 3 is label 1 data. 1 and 5 are label 2 data. 0 is label 3 data because it has the correct type but is outside the range. "five" is label 4 data because it has the wrong type.
  • normal
  • boundary
  • invalid
  • erroneous
  • iterative
  • final
Written answer2 marks

Explain why the value 5 can be both boundary and normal test data in this scenario.

Use the accepted range and the meaning of each classification.

Students type their answer here.

Clinic 2: elements, indexes, return and print

An index is a position used to access an item. An element is the stored item itself. In Python, the first index is 0. A function's return statement sends a result back to the calling code; print only displays output.

Multiple choice1 mark

For colours = ["red", "blue", "green"], which expression accesses the element "blue"?

  • Acolours[2]
  • Bcolours["blue"]
  • Ccolours[1]
  • Dcolours[3]
Written answer2 marks

A function calculates a temperature conversion. Explain why returning the result may be more useful than only printing it.

Describe what the calling program can do with a returned value.

Students type their answer here.

Clinic 3: condition-controlled iteration

Python while repeats while its condition is true. A loop must contain a change that can eventually make the condition false; otherwise it may never terminate.

The countdown below should return [3, 2, 1], but its update subtracts two and skips values. Correct the update inside the loop.

Coding task2 marks
def countdown(number):
    values = []
    while number > 0:
        values.append(number)
        number = number - 2
    return values

Clinic 4: search, Boolean logic and program errors

  • Binary search requires sorted data.
  • GCSE OR produces 1 when one or both inputs are 1.
  • A syntax error breaks the language rules. A logic error allows the program to run but produces an unintended result.
Multiple choice1 mark

What is the output of A OR B when both A and B are 1?

  • A0
  • BThe result is invalid
  • CThe result depends on sorting
  • D1
Multiple choice1 mark

A program runs but calculates price + quantity instead of price * quantity. What type of error is this?

  • ALogic error
  • BSyntax error
  • CTranslation
  • DAuthentication
Written answer2 marks

Correct the claim: ‘Binary search can quickly search any list because it starts in the middle.’

State the missing prerequisite and explain why it matters.

Students type their answer here.

Clinic 5: translators and IDE facilities

A translator converts source code into a form that can be executed. A compiler translates the whole program and can produce an executable; an interpreter translates and executes one statement at a time. An IDE provides tools around development, but it does not guarantee that every error is found or corrected.

Written answer4 marks

Evaluate this claim: ‘If a program compiles and the IDE shows no errors, the program must be correct.’

Separate syntax or translation success from correct program behaviour, then reach a judgement.

Students type their answer here.

Written answer3 marks

Choose one misconception from this worksheet that you held or nearly chose. Write the incorrect idea, the corrected rule and one example that proves the correction.

Be technically precise. Your example must make the difference visible.

Students type their answer here.

Next step

Do not repeat the entire course because of one weak area. Use your clinic notes to choose one relevant topic worksheet, complete its independent task again, then attempt a different exam question on the same idea.