A few years ago in Key West, we were out on the docks and saw one of the most amazing dog tricks I have ever seen. A family had their JRT walking around on a large ball. The dog walked on the ball, bounced on the ball, led the rolling ball around cones and as a finale, jumped off the ball and through a hoop. I wish now that I had asked about it, because I can't figure out where you would even start to train for that. Do you get the dog used to standing on something like a bowl, that is curved but doesn't move? I can't imagine a ball big enough for my future dog (maybe an exercise ball) but it was such a cool trick.