Aang picks up a couple of spare puzzle pieces and sorts them as he answers.

"I was supposed to, yeah. Haven't yet though."

He goes quiet for a few moments, stuck in a memory.
Sep's second question stirs him from it eventually.

"Hmm? Oh, oh yeah. The other have form specific to them. Waterbending is a bit more fluid, and earthbending is all short, strong motions. Airbending is all circular."