Is it a one-on-one lesson?
We will be talking one-on-one with the one who volunteers. ;) If we have two volunteers, we could do it in turns, 15 min for each. If we have more - well, I'll have to draw a lottery, then. :) (Well, last time I did it only one person showed up, so he got a full one-on-one only for him ;D You can see it in recording below!)