Your goal

They should see that 3/6 and 1/2 cover the same amount of one whole — not that there’s a rule for cancelling.

Say this

“Don’t work it out yet. If we cut a chocolate into 6 and take 3, how much of the slab is gone?”

Hints — one at a time

1. 1Ask them to fold a strip of paper in half. How many parts?
2. 2Now fold it again. How many parts now — and how many are shaded?
3. 3“So is the shaded bit bigger, smaller, or the same as before?”

Avoid: telling them to divide top and bottom by three. They’ll do it once and be stuck the moment the numbers change.