M20 instructor pilot reported the student flew an unstabilized approach resulting in a hard landing and tail tie down striking the runway.

Narrative

This event occurred during transition training to Mooney M20. The owner had observed five landings in this aircraft and was ready to attempt their first landing at the controls. Approach to the airport was as directed; with the airplane correctly configured for landing and speeds on target. The flare was slightly high; dropping the aircraft onto the mains; and the rate of descent then caused the nose gear to bounce. My hypothesis is that the owner instinctively pulled back on the yoke; exacerbating the nose-high attitude introduced when the nose wheel bounced; causing the tail tie-down to scrape on the runway. At this point I applied power and assisted with the controls; however the nose gear bounced again and we tapped the tail tie-down a second time before arresting the oscillation and conducting a go-around. I performed the next landing and we returned uneventfully. The skins of the aircraft showed no wrinkling and the only point of contact evident on the plane was the lower part of the tail tie-down.