Avatar: The Last Airbender Season 3 -

The group disguises themselves as Fire Nation citizens. Highlights include Aang attending a local school ("The Headband") and Sokka training under a master swordsman ("Sokka's Master") [24].

Finally turns his back on his father and joins Aang as his firebending teacher [15, 18]. Avatar: The Last Airbender Season 3

Becomes a master swordsman and a tactical leader for the invasion force [4, 24]. The group disguises themselves as Fire Nation citizens