How can a misconception be distinguished from a simple error?
A misconception is an explanatory idea that conflicts with accepted knowledge. One wrong answer does not necessarily reveal such an idea: inattention, misreading or missing procedural knowledge can produce the same result. The distinction changes the support a learner needs.
Making thinking visible
After an answer, ask how the learner decided. Repeating the same reasoning across examples may indicate a more persistent conceptual issue. A learner who thinks every fraction with a larger denominator is larger may be focusing only on numeral size. First check that the whole is the same and the question was understood. Drawings, comparisons and short interviews provide different views of thinking. Focus on the relationship the learner constructs rather than labelling the learner by the error.
Using misconceptions in teaching
Repeating the correct rule may be insufficient. Select examples that reveal limits of the existing explanation, then examine a more coherent account together. Counterexamples should not embarrass learners; they explain why an idea needs revision. Recheck the relationship in a later task. Reciting a rule alone does not establish that a new explanation has been adopted. Teachers should also consider whether their own question or representation caused confusion. Assessment thereby moves from detecting errors toward improving instruction.