The battlefield is set, usually some auditorium on campus, and the sides have been chosen, an audience primarily full of 18-24 year olds sits with funnybones primed to snicker and laugh, but also to silently judge the funniest and come up with "what would have been really funny" and "What I was hoping you'd do" and all those other things that you hear in a compliment that makes you kind of tune out a little bit.
And then you and your troupe. A rag tag team of misfits, usually people who "like to make people laugh" and "gets told I'm funny a lot" according to their membership applications. You have your shows, and sometimes they're good and you party after, and sometimes they're bad and you party after, and sometimes their okay and you go to bed (Parallelogramophonograph).
But what about workshops? What's that going to be like. In short, hell. Yes it will be fun, and yes you'll learn a lot from teaching so much, but it will be hell. However large or small your troupe is, it will probably seem like no one cares as much as you do (that's just your pride talking), it will probably seem like nobodies learning anything (that's hopefully just your worry talking since they did elect you), and the worst is it will probably seem like no ones listening (that's real-- kind of).
I personally got really worked up because people were talking and stuff during practice, but this is a totally normal thing. For one, they're college students who probably spent the rest of the day all cooped up and showed up to practice to get away from that. For two, just like you they are more than likely self-conscious, scared people who by fate have the reaction to fear of "funny" and when they get nervous or when the silence is too loud and no one's laughing they start talking to make sure people still like them.
So what do you do? BAD IDEA: YOU TELL THEM TO SHUT UP!! THIS IS MY WORKSHOP I WORKED REALLY HARD ON AND I NEED YOU TO BE BETTER SO PEOPLE TELL ME THIS GROUP IS FUNNY AND I CAN FEEL ACCOMPLISHED.
Good Idea: Tell people they're funny, but they don't need to do it outside of scenes right now. When people persist, and make a fool of themselves just to get attention, yeah, call them out, rattle a sword or two, but just be nice and assure people, even get all Psycho-babble on them "Hey, I know that right now the attention is on someone else and it's making you nervous, but if you show them appreciation and attention during their scenes, I swear they'll do the same for you."
Come up with your own method for it, but just rest assured, it's got nothing to do with you. Talking while you're talking, just do what teachers do and make it kind of awkward for them, limit the amount you talk so people don't lose interest. ADHD is common among improvisers, so keep your instructions short and clear and if they get miscommunicated then just play with it because as long as they're doing good scenework they're learning, and if they're not it's back to the old drawing board.
Also, don't be too hard on anyone in particular even if in your mind they are the bane of your improv existence, you're much more transparent than you think.