Lupin’s Boggart lessons

It’s been a while since I read PoA so I don’t remember if Draco was in Harry’s class in the book or not. I don’t think so anyway.

But regardless- what do you think the Slytherins’ boggarts were? Because I remember Lupin saying that he wanted the Boggart for his third years, so I would guess that’s for all houses instead of us just seeing the Gryffindor class.