I've done my classes both ways and prefer anchoring. Yes, it can be a bit distracting with the boards moving from side to side, but not nearly as distracting as floating away. Unless you have a class all on the same board type, and with the same body size than they will float at different speeds and I find it more distracting when some are slowly drifting and others are paddling back to the group because they were quickly carried away. Depending on which of my locations I'm teaching out of I have a long rope that we can hold up to 10, they take their leash off and wrap it around the rope with the paddle and then I anchor myself separately and have to be backwards on my board to face them. At another location it's easier for everyone to be individually anchored so they paddle out with their anchors and drop it where they choose. The leash is still taken off but just the paddle is attached to it.