I use a hand distaff when spinning "Roman" and a long one for medieval displays. I still sling the thread under the whorl, as it made the difference between whorl falling to the ground and breaking and spindle falling to the ground and whorl surviving.
For modern spinning I prefer working with the short Roman distaff than holding the wool in my hand. But that's me.
I learn to spin for myself with the help of some books and YouTube. I don't need to pass the thread under the whorl, and in case it helps you can make a small opening at the tip of the spindle. At events I try to use a distaff but this is my problem. I'm not used to it. I try to support it on my belt so it won't fall and my left hand it's free to grab the fibers, but sometimes I find that difficult. Another problem is that with a distaff I have some tendency to break the fibers. I don't know if you can give me some tip, or maybe I just need to get used to the distaff.
I have learnt to spin with a wheel and a drop spindle but I haven't yet got the hang of medieval-style spinning and I can't make my distaff work.
However, I do have one piece of advice for you, which holds true for all craft/textile teaching (and probably a few other things too). If you need to teach a left-handed person when you are right-handed (or vice versa) sit them opposite you and make them copy you as if you are mirror images of each other. My neighbour who taught me to spin was very careful to do this when teaching me to knit and crochet, so I do those right-handed (like I write). However, I just noticed that I spin left-handed, despite being right-handed, because we forgot to implement that when she taught me spinning...
I love spinning with a distaff. I have a long one which I generally use when drafting with a short draw, and a hand held one, that I am just getting good at using, that I use when drafting with a long draw. The biggest problem I had when learning to use my distaffs was keeping a consistant draft. My first spindle-full on each was very uneven. But it just took practice. I worried more about being comfortable holding the distaff than what my thread looked like, and very quickly my thread improved. I hate to spin without one now.
Good luck with your workshop.
I'm still struggling with the distaff, I've tried both long ones and hand-held ones. My biggest problem is spinning with really long fibres (+ 20 cm) but it happens with shorter wool too: everything's fine in the beginning, but after a bit the fibres become wound so tightly round the distaff that I can't draw at all. I've tried arranging the wool as if it were flax on the distaff rather than wrapping the combed tops around it, but it still ended up a bunched-up mess after a while. Haven't given up yet, though...
Spinning with the distaff works quite well for me in the meantime. But one problem remains: the wool, which is wound around the distaff, keeps sliding down: when I start spinning, the wool is on the upper part of the distaff ... some seconds later the whole bunch rests on my hand. I have tried to fix the wool with a bit of yarn, but it did not prevent it from sliding down. Do you have any idea, what I do wrong?
All the best, Michaela