THE STUDENT PILOT AND INSTRUCTOR WERE ON THEIR FIRST DUAL FLIGHT. THE STUDENT WAS ON THE FLIGHT CONTROLS WHEN THE HELICOPTER DRIFTED RIGHT AND THE RIGHT SKID CAUGHT THE GROUND. THE HELICOPTER ENTERED A DYNAMIC ROLLOVER. THE FLIGHT INSTRUCTOR SAID HE WAS MONITORING THE MOVEMENTS OF THE STUDENT, HOWEVER, HE SAID HE HAD LET THE STUDENT GO TOO FAR PRIOR TO TAKING CORRECTIVE ACTION.