Here we see Rose and her Hanoverian Sparrow practicing one-tempis flying changes. When you start training and practicing flying changes, your horse probably knows shoulder in, haunches in, all the lateral work. It knows to move over from the leg aids. If you continue to use strong lower legs you will almost certainly get crooked changes. You must teach the changes off of your hips and seat. The horse follows the rider's hips like a child skipping in a straight line. One of the reasons straight changes are so important is that they can be proof of the horse and rider's connection through the back and seat, and not a trick off the cue of heel and spur.