How should distractors be written for multiple-choice questions?
A distractor is an option other than the correct answer. A good distractor represents a plausible misconception or procedural error. Its purpose is to reveal understanding, not trick students through wordplay. Implausible alternatives are easily eliminated and can weaken the question. Keep the stem and options focused on the same learning goal.
Building options from real errors
In a percentage problem, using the wrong base, treating a percentage as an ordinary number or confusing an intermediate operation can produce different alternatives. Teachers should be able to explain the thinking behind each one. Grammar, length and detail should not inadvertently identify the answer. Clarify context if more than one option could be defensible. Negatives and overlapping alternatives can add unnecessary reading demands. A colleague solving the item may identify ambiguities.
Interpreting response patterns
A distractor nobody chooses may be ineffective, but one administration in a small class is not conclusive. Strong students selecting the same wrong option may indicate ambiguity as well as a learning gap. A brief justification helps distinguish guessing from a specific line of reasoning. When used diagnostically, patterns can inform the next examples to teach. Explaining why the underlying misconception fails is more useful than making students memorise wrong alternatives.