Thanks Ghengis,
Nicely put! The interaction between instructor and student is of course the no. 1 objective. I have done very little lecturing to larger audiences and the relative merits of the different types of presentation is a subject of discussion I use with student FIs.
I have often picked up student FIs for putting too much text in briefings, both pre-flight and long briefings, getting them to think about the reasons for having visual backup to their words.
The posts on this thread are convincing me that chalk n talk is the preferable way to teach student FIs to present most pre-flight briefings, with the use of some form of technology, which could be as simple as OHP where the complex graphics required are beyond the artistic abilities and time constraints.