I am teaching today

and, as always, I have doubts. Have I done enough preparation?
Teaching adults is so very different from teaching children. 
The language I would use for children is entirely different from the language I will use for today's adults. The exercises I give adults are entirely different from the exercises I give children. I will make certain assumptions about adults that I would not make about children, especially very young children.
Today I will assume that the adults I want to teach want to learn, that they want to be there. I will assume they know the difference between "left" and "right", "over and under", "first" and "second".  I will assume adults have the physical skills to manipulate materials and that if I suggest someone turns something "upside down" or "sideways" then they will do just that without me having to show them. 
I also know that they may know more than I do about certain things and that this should give them their own ideas. It is entirely possible I may need to encourage them to try those ideas - but that is what I am there for. I am not there to dictate the way I might dictate to a child - although, if I am a good teacher, I should not need to dictate to the child either. 
But, I have not taught this material before. I wonder how much I will have to try and demonstrate as well as explain. There is a technique that the students may be able to master today. If they can their work will flow. If they can't then the alternative, the one I had to master, will also let them do the job at hand.
And, above all, I want today to be both a learning experience and enjoyable. This is about a craft that is also an art form.
The Book of Kells is more than a thousand years old. There is Celtic art work far older than that. It is still an inspiration today.
Celtic Knotwork fascinates me in a way I never expected geometry to fascinate me.
I want it to fascinate the students too.