The biggest key to success in presenting, it seems to me, is keeping the audience's attention. This appears obvious, but is easier said than done. Long descriptions of wars and treaties delivered without break to an audience will lose their attention quickly. It seems to me as if the surest way to keep an audience's attention is to open up lecture's to discussion with them. If the audience is involved, they cannot lose focus, or likely won't at least, as they have the opportunity to voice their own opinions, and most of us enjoy being heard alone with other people's undivided attention.
In addition to audience involvement, creativity is important in an attention keeping presentation. Diverging from the normal ways of delivering information, i.e. handouts and speaking, and including items such as skits allows the audience to learn information on the time period while simultaneously being amused by the antics and actions of the presenters. If one is amused, one is also more likely to retain the information being given. It seems as though teachers would benefit from occasionally switching up the regular class format if they do not do so already.