This episode is part of the Avatar Book Two - Earth
Avatar The Last Airbender Episode Guide ~ via Wiki
Still looking for an Earthbending master, Aang and the crew stumble upon an Earthbending tournament. While there, they see the blind master Earthbender Toph, a girl whom Aang saw as a vision in The Swamp. Aang challenges her and easily defeats her with Airbending, but she refuses to teach him Earthbending. Both Aang and Toph are captured by the owner of the Earthbending Tournament.