Personal Gain and Private Agendas
Teachers are not servants to the game. The In-Character Teaching Oath states that "Learning is a privilege and not a right." Teachers are not expected to train every student that requests a task. It is the Teacher's prerogative to choose her students and to decide if their work is worthy of reward.
A Teacher is in a special and powerful position. Teachers have the ability to influence, mold, and foster alliances with many other characters. For these reasons, a Teacher can be an extremely valuable role-playing tool.
Teaching with an In-Character personal agenda is an acceptable practice so long as students learn from their tasks or perform a worthy endeavor. Students can pass messages from Teachers, advertise for Teachers, and organize their Teacher's events. There are many ways that a Teacher's personal agenda could come into play within her teachings. Teaching should be rewarding for both the student and the Teacher.
