Harry, Snape and Dementors WAS: Re: CHAPTER Chamber of Secrets Chapter 18:

[pippin_999]

No: HPFGUIDX 189380

 
> Alla:
 
> And my biggest question is how  Snape acknowledging in his head that other methods exist show that Snape was being fair to Harry? 
> 

Pippin:
You mean, is it fair to Harry that Snape thinks he knows more about tackling dementors than Harry does? Read on. 

Alla:
 But if Harry explained it in detail with good reasoning and all that, I think he should have gotten an Outstanding. 

Pippin:
Heh-heh. Harry is in the same boat as Snape. He can't tell how he drove off hundreds of dementors with the patronus spell, not without incriminating himself. And Snape is not supposed to know about it either, since he told Fudge that he had no idea what made the dementors retreat. 

As far as Snape knows, (or at least, is supposed to know), Harry's sole experience with real dementors is with the two he drove away from himself and Dudley. And if ever there was a time when a less conspicuous method of tackling dementors would have been useful, that was it. So that wouldn't be a good example, given that Snape's works, and he wouldn't have been teaching it if he thought it didn't. There is no canon, ever, of Snape  teaching a magical technique that is ineffective when properly performed. He has his many faults, but being Slinkhard isn't one of them. Snape, as we know, tests everything.

So what evidence could Harry have used? There isn't anything in books, or Hermione would have recognized the patronus spell when Lupin and Dumbledore cast it. 

Harry could cite Dumbledore's ability to drive off  the horde of dementors that attacked him at the Quidditch match. But as Snape says, what a wizard like Dumbledore can do doesn't really apply to anyone else. 

It's obvious that Dumbledore didn't want the patronus spell to become widely known even after the dementors defected. Perhaps he also regarded it as too dangerous for the average wizard to attempt, since, as I said, the incorporeal patronus can become a trap for the wizard who casts it.

I wonder what the other DA students put in their essays about it?

Pippin