The snafu was Vader of course. The new private lesson studio is in the downstairs area of my home. I attempted to keep Vader from going downstairs and disturbing the students by creating a huge and high blockade to the stairs made of a giant wooden screen, a tall shelving unit, and some boxes. There is NO way he could have jumped over it. Yet he somehow got through it. The instructor teaching the lesson in the studio walked Vader back upstairs and put him back behind the home made blockade. He got right past it again.
Lucky for us none of the students in the class were cat allergic and they didn't mind him there during the lesson. Vader wants to be where the people are, so he hung out in the pole studio and batted at the curtains and attempted to cuddle the instructor while she was teaching.
It looks like I will have to lock him in the bedroom during lessons. He's affectionate and loves exploring and will hate being locked in a room when he can hear people downstairs. It breaks my heart to have to keep him in one room, even if it is only for 2-hours.