Teaching is a Calling that souls may choose during their invasions on different worlds. Although Hisotry is the only subject we are known to, other subjects may still be used. Before Wanda set off on her journey to the rebel humans, her job was teaching History to other souls.
There are only a few souls who have chosen to teach others, for they may have lived on two to four worlds, but many "Principles" of schools find that Wanda would be a great faculty member (because of her unusually long list of planets she lived on). Wanda chose to teach History at a University in Arizona.
Curt was the soul that requested Wanda to teaching at his school, and she accepted the offer immediately. Wanda loves to teach since it is fairly close to the Calling she had chosen during her time with the See Weeds (Storytelling).
Wanda tells her students in her History class all about the planets she has lived on, including the See Weeds', the Bats', the Bears' and the Origin. Faces Sunward, a student in Wanda's History class, was one of the only ones to ever be outraged with Wanda's teaching. This was mostly due to her telling of the Fire World, and how the fire-eating inhabitants unknowingly killed other sentient beings to survive.
Wanda thought she would never teach again after she ran away from the souls and to the rebel humans, but after a few weeks of being prisoner, and then living among them, she started to teach the inhabitants (especially about her past planets).
If Wanda ever teached again is unknown, but it may show up again in the sequels, The Soul and The Seeker.