Avatar: The Last Airbender 1x16 Reaction

The Avatar usually learns the elements in a specific order, which is the order of the Avatar cycle: Water, Earth, Fire, Air. It's not necessary though.

''If anything happens to Apa''.Interesting...

There was a bit of The Karate Kid in this episode, with Aang being impatient with his training. But along with it establishing that Katara has healing abilities, it shows that Aang thinks differently than previous Avatars. That's very important going forward. He is the reincarnation of Roku, Kyoshi, etc....but he's a very different person than they were (along with having to master everything in 6 months which took them years).