When I do it, I tell them that they can't date the same question they have already seen. Since they are switching cards, they can date the same person multiple times, but not the same question. I also call myself the matchmaker. When ever someone seems to be slow to pair up, I pair them with someone else. You could also try telling them that they need to have a specified number of dates. As far as the concentric circles, you can split the class in two and tell one group to form a circle. Once that is done, tell the remaining group to go stand in front of someone in the circle. This is the fastest way I know to set them up. Good luck!!