This drill works on showing the dog the difference between serpentine and threadle cues.
A serpentine is a handling maneuver that cues two turns but there is no side change...basically an "S" pattern. The dog takes the obvious side of the jump they see. They jump towards the handler over the jump and end up making two turns - in the example diagram above, the dog makes a left turn from #2 - #3 and a right turn from #3 to #4. Serpentines are most commonly seen with 3 jumps, but a serpentine can use any 3 obstacles.
Serpentine Position -
Handler should be an arm's length from the top wing of the jump, don't be too wide from the jump. You should be able to see the dog between the wings when giving the cue. The cue is - the arm closest to the dog, pointing back towards their nose, shoulder is open backwards to invited dog to jump towards you. Your feet should be pointed at the next obstacle. Keep moving towards the next jump when dog is committed to serp jump. You want to be in this position when the dog is landing from the previous jump.
You need to be ahead to serpentine, this will help you connect in the right place (notice in the video example when I was behind and cued my serp too early, I pulled Chip to the wrong side of the jump). It will also help you stay out of the dog's landing zone (the danger zone), if you're in their way you risk a collision or a knocked bar.
Serpentine foundation is very similar to recall to heel.
Threadles cue the dog to go to the opposite side of the jump they see. There is no side change.
You should be using your opposite hand to cue it - if the dog is on your right side, use your left hand.
You should use a consistent verbal cue like "come come" or "in in"
You want to connect with the dog before the threadle jump, on the path you want them to take - "outside the wing".
Try to avoid over rotation, you want to keep moving forward when the dog is committed to coming in for the threadle. Your feet should be pointed in the direction you're going next.
Threadle Rear - a threadle followed by a rear cross, resulting in a side change.
You can use the same threadle verbal cue as a regular threadle, or you can have a specific cue word for a threadle rear.
While cueing, you want to rotate in the direction you're going next. There is more rotation on this that a regular threadle.
Stay farther away from the jump you're threadling, you want to be closer to the jump you're going to next. Stay "outside" the wing.
You can see threadle foundation training in this post.
If you have 6 jumps, you can make the whole circle that is shown in the video. You can do it as numbered then reverse it and do it the other direction. You can also mix and match, do a serp on the first half and a threadle on the second half.
You can also do the same drill with just three jumps. It's also a good idea to practice coming from an obstacle besides a jump. So you can make #1 weaves, a tunnel, a contact, plank or table.