Choose a Counterexample

Worked model: Choose a Counterexample

1. 1Ask learners to find a case that would challenge a broad rule and revise the rule accordingly
2. 2Find a case that would contradict it if true
3. 3Check whether the case genuinely meets the stated conditions
4. 4Revise or reject the claim using the counterexample

Worked classroom example

Claim: all rectangles have unequal adjacent sides. A square has four right angles and equal sides, so it is a rectangle that challenges the claim.

Teach the move

1. 1

   Ask learners to find a case that would challenge a broad rule and revise the rule accordingly.

2. 2

   Find a case that would contradict it if true.

3. 3

   Check whether the case genuinely meets the stated conditions.

4. 4

   Revise or reject the claim using the counterexample.

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Teacher language

Adapt these prompts to the task and your learners.

Across subjects