As a dance instructor, I regularly teach in two different ways: one on one in private instruction, or one with many for a group. In a lot of ways, the one on one instruction is much easier. It’s not hard to keep your focus, you get constant feedback from your audience, and it’s very easy to adjust the material, as you go, to make it work. The timeline is also quite flexible – if you get something started, and aren’t able to finish it, there’s always next time. With sufficient disclaimers and communication with the student, you can leave off in the middle of a concept and just pick it up again later.
On the other hand, teaching in front of a group brings up certain challenges. You have to have a plan that can address a group of people with varying interests and skill levels. Your plan has to be flexible enough to adjust to the struggles and questions that arise during the process. You have to address yourself clearly enough to be understood by people with a variety of interest levels, abilities to focus, delusions of grandeur and even different native languages or hearing difficulties. You have to be able to handle problems, questions and even challenges from students without sacrificing the quality of the instruction being given. You have to keep your focus on the group without getting distracted or getting sucked in to the issues of a particular student. And you have to be able to do it all in a finite period of time.