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3
The expected behaviour specifies three.
Beginner · Other / specialist pathway · Coding
Find, explain and fix a bug
Find a bug by comparing expected and actual behaviour.
Original Kidemy beginner self-study unit · Learn the idea, try the practical activity and review your written answers. Review your project with a guardian or teacher using the criteria below. Teacher-led course approval and booking are separate.
Learn the idea
A bug is a mistake that causes a program to behave differently from its intended rules. State what should happen, test what does happen and trace the steps to find the first difference. Change one relevant thing, then test again, including another input.
Worked example
Expected: show a message three times. Actual plan: repeat 4 times, show the message. The repeat count is the first mismatch; changing it to 3 fixes this particular bug.
- Write the expected result before changing the program.
- Trace or run a small example.
- Retest the change so a guessed fix is not mistaken for a working one.
Your written practice
Show your working on paper and enter your answer here. If it does not match, compare the model and try again.
Show model answer and explanation
3
The changed count matches the intended rule.
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retest
The changed program must be checked.
Write in your own words. A guardian or teacher should review this response.
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The operation is subtraction instead of addition. Use 4 + 3, which gives 7.
Check the expected operation and the verified new result.
Write in your own words. A guardian or teacher should review this response.
Show model answer and explanation
Choosing garden opens no scene. I expected the garden scene with a next button.
Check the action, actual result and expected result.
Fix and prove
Ask a partner to put one mistake in a paper algorithm. Find it, explain it and test the correction with two cases.
Review with a guardian or teacher
- Describe the expected behaviour.
- Identify the first wrong step.
- Show what each retest produced.
Keep your work on paper or in a local file. This page does not upload it or automatically grade the project.
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