I've done workshops with this age group a bunch in the past.
One immediate tricky thing is that the variance in skill level is likely to be very wide. You're probably going to have one person who's so good you could see them going pro in a few years, one or two who feel like they've conquered Everest if they manage to just draw an okay looking front view face and will just want to repeat doing that over and over, a few who feel confident when they're copying or tracing and who get very uncomfortable and self-conscious about anything outside that comfort zone...
Consider having lessons where there's a "basic version" and then an optional way to add some more advanced techniques to the same activity for the few kids who blaze through it and want something more difficult. So say, the "basic version" is just "draw a well-proportioned face using guidelines" and then the more advanced one might be "try some of these different hair and eye variations" or "see if you can draw a head turnaround." Or say, the "basic activity" is "Draw Pikachu in pencil" (learning how to construct Pikachu from simple volumes and use pencil weight variation when sketching) and then the advanced optional part is inking the drawing, erasing the pencils and adding some colour.
Oh and hopefully you won't get this, but I've got it almost every time; you'll often get some Karen mum who insists on having their like... eight year old join the course because "he's very mature for his age and he loves manga." and then complains at the end that the class was too advanced for him... Another good reason to have some very low-level, simple versions of activities prepared.