It works and its easy!

Ten meter circles: an epiphany.
To ride a clear ten meter circle with the hindquarters engaged and the horse softly on the bit going toward collection: the horse's outside foreleg abducts around the circle to turn the horse. The key is to bring your inside shoulder toward the horse's outside hip to keep the correct bend and engagement. The inside rein creates just enough bend, but DO NOT "hang" continually on the inside rein, rather give the inside rein periodically while keeping the horse in the outside rein, and keeping the horse's neck between the aids.
Thank you, Karen, for the giant light bulb hanging over my head during our lesson today!