No... Aang already knew airbending before the beginning of Book !, so all they needed were three for him to learn water, earth, and fire bending
Not to mention, the entire air bending tribe is wiped out. So it would be a rather uneventful series.....
There is no book 4 of Avatar the Last Airbender.
Avatar ends in book 3
no
there is no book 4 however, they are working on Avatar: Legend of Korra
There is no Book 4, as the series ends with Book 3, but a new series will come out in 2011.
no
yes
yes
never
there is no book 4
To be honest their will not be a book 4 of avatar the last airbender though nick staff is maybe going to make a avatar based cartoon.
there is no book 4 the show ends with the 4 part finale in book 3. -------------------------------------------------------------------------------------- well my answer is that there IS going to be AVATAR BOOK 4: air.. u c? it is comming out in summer... there zuko needs to find his mother and the avatar has to find another airbender ;) hope i helped.. good luck