The Jan/Feb Society of Children's Writers and Illustrators's Bulletin includes an article by Susan Salzman Raab called Public Speaking Primer. I zeroed in on it because I'm still obsessing over my upcoming school visit, and what is a school visit but public speaking? The public you're speaking to is just sitting on the floor at your feet instead of in chairs.
While describing a presentation's content, Susan says, "Lay out a roadmap for your speech. First, introduce your audience to topics you'll cover, then expand on each of them in the middle of your presentation, finally, close by recapping key points."
This, folks, is what I'd call the classic essay format--Introduction, elaboration, and conclusion. Or, you might also say, Tell them what you're going to tell them. Tell them. Tell them what you told them. I do use something very similar with my two standard presentations for schools. "Today, we're going to talk about...." Then we talk about it. Then I conclude with how they can use what we talked about in their own writing.
I think this is a good format for a speech or presentation. Years ago, I was sitting in church, actually listening to a sermon, when I realized that the minister was using topic sentences. She had written out her sermon in an essay format with a thesis statement and topic sentences that kept referring back to the thesis statement. Though I have no recollection of the sermon now, I was able to follow it quite easily at the time, which doesn't happen for me when I'm listening to ministers who are relying on Divine inspiration instead of good essay writing skills when they're standing at a pulpit.
By the way, I met Susan Salzman Raab while standing in line to get something signed at last fall's Connecticut Children's Book Fair.