Some old formats - - from Marginial Revolution:
1. Chalk and talk. Or with Powerpoint.
2. Play a video and comment on it.
3. Panel discussion.
5. Manage an audience or classroom discussion.
6. One person interviews another or interviews a panel. Or, one person interviews another and children burst into the room, only to be pulled back by their mother. This latter option seems popular right now.
7. All Q&A, no talk (one of my favorites).
8. All questions, no answers allowed from the speaker (never seen this one, but it does produce audience participation).
9. Read aloud from one’s book (the worst).
10. Play or sing a song, or perform in some other manner, such as doing periodic magic tricks. Chat or trash talk while attempting basketball free throws.