Barty at Hogwarts disguised as Mad-Eye Moody in Harry's 4th year
Who? Mad-Eye Moody(Barty), Harry, Ron, Hermione and a class of 4th years.
What? Mad-Eye(Barty) teaching the class spells
When? Harry's 4th year in his Defence Against the Dark Arts class
Why? Because Barty needs to be able to teach as Mad-Eye Moody
Barty had just taken a swig of Polyjuice potion from Moody's hip flask and turned to
face the class. It was the 4th years first Defence Against the Dark Arts lesson. He had
to convince them that he was Moody. His eye swivelled as he took a look at them all.
Where was Potter? Ah, he saw him next to Weasley. Perfect.
'Right. This is your first lesson in my class,' Barty turned and grabbed some chalk from
the table.
'Alastor Moody, Ex-Auror..your new Defence Against the Dark Arts teacher. Any questions?
No? Good bye the end,' he looked quiizically around the room.