An instructor pilot and his student suffered a tail strike on landing when the C172 became airborne after touchdown and the student's hand; frozen on the throttle; prevented the instructor from initiating a go-around.

Narrative

The tail strike being reported here involved a Cessna 172 in which a post solo private pilot Student and I; the Instructor; were aboard. The Student was manipulating the controls while remaining in the pattern to practice landings. The approach to the runway was stabilized at sixty knots with full flaps. After a seemingly uneventful landing; the student applied a small amount of back pressure to the yoke; which resulted in the aircraft floating off the runway approximately twenty feet. As this occurred I; the Instructor; attempted to apply full power. With the Student's hand on the throttle; I was unable to advance the throttle. As the airspeed bled off the plane began to sink back to the runway; at that time the student jerked back on the control yoke. With my hand on the yoke; I resisted this action but was unable to stop it completely. This resulted in the tail striking the ground; followed by the landing gear. With the plane on the ground the Student was then attempting to advance the throttle to take back off. I; the Instructor; immediately said; 'stop!' The Student then released all controls and I taxied the plane to a parking spot and shut it down. Corrective actions will be to ensure the Student understands that a go around is the only option in that situation; also; ensuring that the Student knows that when an Instructor is trying to apply input to any control it is for just cause and not to resist the input. Another corrective action will be to review the go around procedure and when it is necessary before every flight with a student.