Seeing as I help teach Agility classes perhaps I can help you a little.

You have to remember that people teach differently then others and it could take you a little while to get used to this new teachers style.

When we first start agility classes the head instructor goes over some of the rules of the class and the building and also over some of the things that students might need in the class. From there we go straight to the tunnel, the head instructo likes to explain each obstacle as she goes along.

As for Jack I actually go through the same thing with Beaker, only also inculde the IG need to zoom around the room at break necking speeds. What I've learned to do with him is either keep him focused on me while we are waiting our turn by working on other commands, flat work, or on attention commands or I keep him up in my arms unless of course I have his kennel there and then he goes in to his kennel while waiting our turn.

The waiting game is a big thing in agility classes because it's not like obdience classes where you can work on the stuff as the same time as everyone else. That's why I always find it good to work on the other stuff with my dogs while I'm waiting. Some of the things that I do are things like getting the dog to follow my lead hand, which doesn't need any equipment at all. I also do target work with my dogs where they target my hands which will later help when we are running on course because they learn to watch my hands. I have also be known to work on my side changes while waiting or even just working on the dogs commands for the side changes. It's also fairly easy to do attention work while you are waiting as all that really takes is praising your dog everytime they look towards you...I could explain that in more detail if you want.

Jack could have been acting like that for the first class because it was a new place, with new smells and new dogs. I've seen plenty of dogs that are really excited and hard to control for the first week or two of classes but who eventually settle down as they get used to everything going around them.