Find out what the students are interested in. Just do a quick survey. Then starte with the majority answer and see if you can find a parent that works in that field and would enjoy coming to talk about their profession. If not, get the community involved. I don't think that there is a business around that wouldn't mind sending one of their professionals to talk to the students for about 15 to 30 minutes. It could even be subject based visits. Have a doctor come talk to the biology class. Have a historian or museum person come talk to the history class. I had a couple of my kids that wanted to be teachers. So you could even just have the teacher talk to the class and tell their story about how he/she wanted to be a teacher and what all was involved in becoming one. In either case, you would give the students a break from their day to day classes and, at the same time, they would get insight, as well as interest, in what direction they might want to go when they graduate from high school.