If I evaluate the crowd of dancers and they require a lot of instruction for a move that they will see once in a evening (like the star promenade) then I get on the floor and do a demonstration. 

I see less and less Callers teaching/demonstrating from the floor in the dances I attend on regular evenings.  And more often it seems that the Callers are relying on the experienced dances to teach the newcomers during the dance, which is a completely different discussion.

Donna