"Bigger would be of help," he said. "But how can a place be portable?" he asked. "Well, I suppose a tent could be, or a hut if the circumstances were correct." Yes, his sliding off topic was mildly deliberate. He's in a strange new place having to learn fast. He has to have some fun somewhere. Plus it'll be good practice for Zuko to hold his temper, and be good for the boy to feel like the smarter one in the room for a bit.