Congrats! I've been invited to interview at Chatham as well, and I've talked to a few current students about the interview process. I was told to prepare for a written portion and to draw from a number of experiences that would demonstrate to the committee that you'd be well-suited to problem-based learning. Specifically, I was told to talk about more than just my aide experience. I'm hoping to get a chance to talk to the students a bit more in depth, so if/when that happens, I'll let you know!