I've heard of the episode titles being
36 When There was you and me
37 Aang's Calling
38 Appa's Lost Days
39 The Last Koufus
40 The Failure
but I've also heard of them being
36 Appa's Lost Days
37 Lake Longai
38 the Earth King
39 TBA
40 TBA
I don'r know which ones are true if they are true at all