a) In her first lesson Hayley showed clear tension in her upper body, hands, elbows and shoulders. Her hands appear to be fixed. This causes inconsistent bit pressure. No horse will move into a round steady flexion frame ('on the bit') when bit pressure is inconsistent.
b) At the end of lesson three Hayley is now relaxed in her arms and upper body. Her arms are moving with the horse's mouth with elastic contact. This relaxation is reflected in the horse even though Hayley's hands are slightly pronated. Consequently the horse has rounded his frame from his nose to his hind feet. This has produced more engagement and has lifted his back.