I have had to "teach" most of my working life, having been a Head Chef for over 3 decades and I start by apologising to treat them like beginners, newbies, but to bear with me as I have to ensure everyone knows the basics.
I do the same with my Patchwork classes having been to a workshop at the 1st Loch Lomond quilting exhibition in Scotland, when the Tutor starting to "assume" that we knew certain things, she realised very quickly that we didn't and kudos to her, completely changed her lesson. I took note and my first lesson is ALWAYS on how to clean and look after your sewing machine, how and when to change needles, threads etc. I am so grateful to that Lady, as my group members are now able to look after their machines.
By coincidence I went to a talk with Dawn Cameron Dick today at a local quilters group and she said that so many people say "Oh I must buy another machine, this one isn't doing what I want to do" and she replies "Look after and keep your machine, change your needles regularly, using the correct ones according to the fabric and thread you are using, isn't that what the famous saying does "It is a poor workman who blames his tools"!
One of the best sayings I have learnt is " Never assume"