OK, this is a bug. Thx for reporting and enduring. But there is hope. Talk to Tanya in the dorm in the morning, weekday, between 7am and 8am. Also between 8 and 9am in front of the college (mouse over sprite shadow). Both times make no sense, this event should be possible in the evening or during the weekend only. ... Followup: after the sleepover there may be another bug. You have to find Bonnie and Tanya in the College but you will just detect their mouse-over shadow again. CLick on it to get the teacher job.
Sorry for the mess, dev added some scenes lately and crashed the old ones. Will be fixed.