Narrative:

Student was doing a soft field takeoff and pitched too high and stalled the aircraft. I said 'I have the controls,' but the student froze and didn't completely relinquish them to me. I finally pulled the mixture to idle cutoff and brought the aircraft to a stop.

Google
 

Original NASA ASRS Text

Title: AN SMA INSTRUCTOR PLT HAD TO TAKE OVER THE CTLS WHEN HER STUDENT PLT STALLED THE ACFT ON TKOF.

Narrative: STUDENT WAS DOING A SOFT FIELD TKOF AND PITCHED TOO HIGH AND STALLED THE ACFT. I SAID 'I HAVE THE CTLS,' BUT THE STUDENT FROZE AND DIDN'T COMPLETELY RELINQUISH THEM TO ME. I FINALLY PULLED THE MIXTURE TO IDLE CUTOFF AND BROUGHT THE ACFT TO A STOP.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.