Exam Mistake Analyzer — illustrative example

INPUT
Student answers 2/5 + 1/5 as 3/10.

RESULT
The denominators represent equal-sized parts and stay 5. Practice common-denominator addition and explain why the answer is 3/5.

REVIEW
Mistake analysis should identify the reasoning step that failed. Classify recurring patterns so the next practice session targets a cause rather than repeats everything.

This is a teaching example, not a live execution record.