Non-Examples

The steps

1. Write down the misconception first. Predict the wrong rule students are likely to build if they only ever see correct cases. In English it is often "a simile is any sentence with 'like'". Your non-examples exist to break that rule, so name it before you plan anything else. If you cannot predict it, last year's wrong answers will usually tell you.
2. Choose near-misses that fail on one feature only. A useful non-example matches your true examples in everything except the one feature that matters. "He looks like his brother" contains 'like' and a comparison, yet it is not a simile, because the comparison is literal. Keep every case close enough that some students would genuinely say yes to it.
3. Teach the clear examples before the edges. Show two or three true cases and name the feature that makes them count (Example First). Students need a firm picture of the concept before you begin to test its boundary.
4. Show a true example and a near-miss side by side. Ask the class to find the difference, and give thinking time before you take an answer.
   Both of these use the word 'like'. One is a simile and one is not. Thirty seconds with your partner: which is which, and what is the difference?
5. Have everyone classify a mixed run. Show six to eight cases one at a time, in an unpredictable order: true examples, near-misses, and one or two easy cases. Everyone answers every time, on boards or with a thumb (Show-Me Boards). After each verdict, ask one student for the reason:
   Not a simile. What is it missing?
6. Return with new boundary cases later. In the next lesson, bring two near-misses the class has not seen, harder than the first pair. Keep a note of any wrong rule that survives the week. When the class later meets metaphor, similes can serve as its non-examples.

How you’ll know it’s working

• The reason comes with the verdict. Students reject a near-miss by naming the missing feature rather than saying that it "doesn't sound right".
• Wrong votes on the classify run shrink across the sequence: perhaps ten boards wrong on the first near-miss, then two or three on the new cases a week later.
• Students begin bringing you their own boundary cases during practice: "Does 'as if' count?"
• In written work, the term stays inside its boundary, with fewer literal comparisons labelled as similes than before you taught the pair.

Weigh it up

Why it’s worth it

• The predictable misconception surfaces during the lesson, while there is still time to address it, rather than three weeks later in a pile of marking.
• One good pair often does more than three restatements of the definition. Students see where the boundary runs instead of hearing the same words repeated.
• The classify run doubles as whole-class checking: every board shows you who holds the concept and who holds the too-broad rule, and the same run can serve as retrieval practice weeks later.
• Boundary knowledge is the kind that transfers. A student who can say why "looks like his brother" fails can recognise a simile in an unseen poem and explain why a metaphor is not one.
• The pairs are reusable: a bank built this year works again next year, and drafting the near-misses sharpens your own picture of the concept.

The costs

• Genuine near-misses are hard to write. The obvious non-examples are usually too far away, and a good one can take longer to find than the rest of the explanation.
• The sequence takes lesson minutes that a definition and two examples do not, and for simple concepts that time buys little.
• The near-misses catch students out publicly, by design. In a class where mistakes do not yet feel safe, the classify run can feel like a trap, so that culture has to be built first.