I did a one day trieball workshop with Becca last fall. Since the workshop I've had a hard time finding a class. Becca's chief problem is that she pushes the ball open mouthed. I'll check in with the trainer who did that workshop and see if she has any contacts.
At our dog training school they teach Treibball. Looks so fun. I do know that there they want you to have completed an advanced obedience class since you are working your dog from 20 ft. away sometimes.
I've wanted to get into it. I was thinking of going to a dog camp where treibball and flyball classes are offered which would be an easy way to try both.
I emailed the trainer that ran the workshop I attended. She said, "The American Triebball Association is the only one that seems to up and functioning right now. Dog Scouts also has a triebball course. "
I live in Michigan and the trainer at our school actually traveled to Colorado to get certified by the Amer. Treibball Assoc.