Revise with a Counterexample

Worked classroom example

Across subjects

Worked example

“All rectangles have unequal adjacent sides” fails for a square. Revise to “A rectangle has four right angles; its adjacent sides may be equal or unequal.”

Use this example to make the language move visible. Select subject content appropriate to the class’s age and prior knowledge.

Teaching sequence

1. State the proposed claim clearly.
2. Check it against a supplied counterexample.
3. Decide whether to narrow, qualify or replace the claim.
4. Write the revised claim and explain the change.

Try it in your next lesson

Prepare

Use a general claim and an exception. Choose a second example that checks the same language move without repeating the original answer.

Classroom task

Improve a general claim by testing a near miss.

Check independent transfer

Give a new claim and ask learners to supply or test a counterexample.

Collect a response on fresh content. Note what was achieved without the model, partner or teacher prompt, then choose one next teaching step.

Teacher language

Teacher language

Which part of the claim does this case challenge?

Respond to the learner

Identify one successful meaning or language choice. Ask about one gap, allow thinking time, then invite a revision. Check the revised move again on a fresh example.

Adjust support and challenge

Offer a brief model, useful vocabulary and partner rehearsal where needed. Keep the subject goal; reduce one prompt on fresh content and record what was independent.

Teaching this skill → · Age and language support →

More support

Use oral rehearsal, a brief model and a limited sentence frame. Remove one support for the fresh writing task. Allow familiar-language notes or another response mode when checking subject understanding.

Greater independence

Change the content, evidence or audience. Remove the completed model and ask learners to explain a choice. Increase subject complexity only when it fits the curriculum and prior knowledge.

Choose the next step

If subject meaning is insecure, reteach the concept. If the concept is understood but the English is unclear, model one useful language relationship and invite a fresh response.