If teaching for the IMC Rating, only the actual time when you, yourself are handling the aeroplane 'by sole reference to instruments' may be logges as 'Instrument Flight Time'. However, the whole flight may be logged for the utterly meaningless JAA 'IFR conditions' purpose.
60 min flight, FI handles ac for 10 minutes by sole reference to instruments, student for 30 min. Assume the whole thing was IFR:
FI: 0:10 min Instrument Flight Time, 1:00 IFR conditions
Student: 0:30 min Instrument Flight Time, 1:00 IFR conditions....