I teach four year olds, and when we look at applicants doing a working interview in my room, we look at how well the assistant interact with the children. We don't want them to wait until they're asked, we want them to more or less immediately assess what needs to be done, and do it, whether it's playing with the kids outside, sitting reading to a small group, helping with snack, or just sitting behind a trouble spot in circle time. Most important - be honest. They want to know if you are more comfortable with certain age groups, certain tasks, etc. No one will be happy if you aren't honest. We've had applicant say that they like all ages, and then quit when they get the 'wrong' one. That's traumatic for all.