In fact, I'm not sure who taught whom.
I'm a big believer in teaching all agility obstacles from all sides at all times. So, if I'm teaching weave poles, we practice equal quantities of the dog entering on my left and on my right from both ends of the weaves. If teaching tunnels, we practice equal quantities of the dog entering from my left and from my right to both ends of the tunnel.
I haven't worked a lot with Casey, although he's a smart, fast, agile little guy. Mostly what I have taught him is tunnels and some jumping. He can usually, with a little backchaining, do a couple or 3 jumps or jump/tunnel/jump in a row.
With the nationals and all, I hadn't really been doing anything with Casey for a couple of weeks. So I decided it was time to put him through a couple of tunnels. Lo and behold, somewhere along the line he has learned to NOT go through a tunnel when I am on his left and I am aiming him at the left side of the tunnel.
I thought perhaps it was something about Tunnel #1 in the northeast corner of the yard. But nooooo-- for all 3 tunnels, he will go into the right end no matter which side I'm on. He will go into the left end if I am on his right. But he will not go into the left end if I am on his left.
I even tried to trick him by sending him in quick succession into the right side with me on his right, then on his left, then into the left side with me on his right, then with me on his left--and he skids to a halt and won't go in.
Dagnab the little brat!