Jane's Extra Credit is one of the routes in Adventure High.
To access it, you have to enslave Jane and complete her four private classes.
Upon doing so, speak to her again in her classroom for another scene in which she suggests you start enslaving random students that come there for extra credit classes.
The First Extra Credit
When the Protagonist later returns, a student is there. The Protagonist explains that Jane is going to teach some debilitating magic.
The student, confused, asks why not get help from Drape, the actual teacher. The Protagonist, bluntly, asks if she has met with Drape, who agrees it is a fair argument.
The Protagonist casts the Suppression spell and starts to enslaving the student, at Jane's encouragement. The Protagonist can either enslave her or let her go.
Enchantment Magic
Coming back to Jane's class, Jane tells the Protagonist to learn about enchantment magic. The Protagonist asks if there's any form of magic Jane doesn't know, but Jane urges the Protagonist to cast the Suppression spell on the blackboard.
Minutes later, another student appears and explains that she's there due to a bet - if she can solve a math test that Jane created, she'll get extra credits. While solving it, the spell that the Protagonist left in the blackboard is unleashed and the girl becomes a slave as well.
Note
- This route might be a minimum floor requirement or possibly only possible if you do it on the enslavement route.