Professor Moody in book 4

[samnjodie <englishatjodie@hotmail.com>]

No: HPFGUIDX 51797

I am just re-reading the goblet of fire and I am confused by some 
apparent inconsistancies regarding Professor Moody. There are a few 
others, but this is the big one; his identity was taken over by 
Crouch from the night before Moody came to Hogwarts, so thereafter 
Moody wasn't really Moody anymore.  But then why was he so eager to 
teach the defense against the dark arts classes about the 
unforgivable curses and how to repel them?  Isn't this the last thing 
a death eater would want non-death eaters to be able to do?  

samnjodie