The certificated flight instructor (CFI), of the Cessna 172SP, stated that the purpose of the dual flight was local air work practice, followed by takeoff and landing practice. After one high approach that terminated in a go-around, then a successful landing, the student pilot departed and positioned the airplane at a higher altitude than normal on the final approach. The CFI took the controls and demonstrated a sideslip maneuver to the student. Once the airplane lost some altitude, the CFI "…turned over the controls to the student and asked him to land the airplane." The touchdown speed was higher than normal, so the CFI queried the student whether the power was reduced, then instructed him to apply aerodynamic braking. The airplane did not appear to be slowing, so the CFI attempted to go around. He applied power and pulled back on the yoke in an attempt to take off, then saw the airport perimeter fence approaching, and felt a "jolt." The left main landing gear impacted the airport perimeter fence off the departure end of runway 1, then the airplane impacted a guardrail, and came to rest inverted on an adjacent road. The tailcone separated from the fuselage just aft of the cargo compartment. Neither pilot was injured. The CFI reported that there were no mechanical malfunctions of the airplane prior to the accident.