Duncan and Me

I'm an EFL teacher. I have an adorable student named Duncan. I know he is smart. I know he understands, but why, why, why??? ARRRGGGHH!

Duncan knows "fish." Duncan knows "shop." He can spell them, write them, say them, and even talk about them in conversation.

So, today I ask Duncan, trying to prompt him on a homework question he was stuck on "What do you buy at a fish shop?"

"Rabbits?" he offered. Must be some of those deep sea rabbits...