Pushing Buttons

I arrive at nursery to pick J up.

Me: How was his day?
Nursery assistant: Fine, ate all his food, but didn't have a very long sleep.
Me: That happens... And what's he been up to?
Nursery assistant: He pushed a doll around in the trolley, did some painting and climbed on some furniture.
Me: Did he now?
Nursery assistant: Yes, and laughed when we asked him to get down.
Me: Ah.
Nursery assistant: Yeah, he finds it really funny. Cheeky monkey.

Back home, I relate the story to W.

W: Well, he is doing that more and more lately. Except at home he seems to find clever ways around things. Whenever I tell him not to do something he tries a subtle variation. When I told him to sit down in the bath the other day, he slowly lowered himself just enough to touch his bottom down and then quickly stood up again. He enjoys it.
Me: I know what you mean. When I said not to pull the books off the shelf the other day he stopped, but a second later started prodding them gently. All the time watching me for my reaction.
W: He knows!
Me: Seems so.
W: It's all about experimenting with what's allowed.
Me: Even if he doesn't understand everything we say, he's modifying his behaviour because he knows something is wrong.
W: It's fascinating.
Me: We've always got to be one step ahead.
W: Sometimes three or four...