Very casual, the supervisor essentially explained the job to me and asked if I wanted and was willing to do it. Most of the "interview" questions where normal in-the-box questions (tell me a little about yourself, what made you want to apply for this job, what type of skills do you have that would make you an outstanding candidate for this position, how long do you plan to be with the department)

I inquired one of my professors about the opportunity and she invited me to her office to talk about it one day. We discussed the position and she asked me a few questions about what I wanted from the position. At the end of the meeting she offered me the position.