I did search this and no ones came up, so sorry if this has already been answered.

Re-reading POA I noticed that when the dementor comes onto the train and Lupin gets rid of it, Hermione doesn't know what it is, but surely after Dumbledore had mentioned they would be stationed at the entrances and exits, I would've assumed that Hermione would have gone to research about them. I know she may have not had time, but she must have had some spare time at one point to spend ten minutes in the library to research them? I always wondered why she didn't. Because at the Quidditch match when they arrive on the pitch, she says in the Hospital Wing [just from memory] 'shot some silver stuff at them.'

I'd just like to here something on it. [:

Dumbledore mentions that the Dementors will be stationed outside the school grounds at the Start of Term Feast, immediately following the incident concerning the Dementor on the Hogwart's Express. So your time-line is slightly
skewed regarding whether or not she could have done research.



There is an aspect to this that can be considered, but it takes some speculation. Naturally we are comfortable with speculation concerning the Potterverse considering most of us spent the entire era theorizing and dreaming up scenario after scenario to explain the mysteries and lingering questions. We have to decide whether we think the Ministry would keep the topic of the Dementors classified or not. We know that everyone knows about the Dementors, and they fear them, but do they really know that much about them? Would the Ministry allow details on how to evade/defeat Dementors (the patronus charm)? Would Fudge utilize the Dementors as personal guards if he knew it was easily obtained knowledge that repelled them? Perhaps any record of the Dementors, besides a basic description, had been magically omitted from Hogwarts Library seeing as they were guarding the castle. These are notions we need to take into consideration and decide which is most plausible.

If you think about it, why would she try and research them. they are so vile and foul. Plus, in third year you go to Hogsmeade, so she could have been looking forward to that.
And Sirius trying to kill Harry, Hermione would have wanted to be there for him.
And lastly, what spare time, she probobly forgot by travelling time and doing all the subjects she kept.
There's my answer anyway, hope it helps:)

OMG, May was the last post? Oh well I'll post anyway, I'm bored.

Yes, I have to say I agree with both Albus Dumbledore and Joey Ravenclaw, and the library may not have permitted hermione to look up this specific topic as it may not have suited her age, or infact the might not have had they information at all, but who knows.

Rach

I think the headmaster probably put information about dementors in the restricted section because of how dark they are and because everyone who has ever been near a dementor is extremely scared of them. Dumbledore hates dementors so he may have completely removed the topic from the library or moved it from the general area.

Hermione may have also just wanted to avoid the subject all together it is not like she had to look up every single thing even though she looked up mostly everything. I mean she did have an OK social life.

Knowing Hermione, she probably did try to research them. However, due to the ministry most likely keeping information restricted, and Hermione's very busy class schedule, she may not have been able or had the time to learn more than the scant basics that any wizard would know.

I dont think Hermione had the time to research. She was strained through out the year from the pressure of her classes. Because of all the classes she had she hardly had any free time. Also i dont think she had the need to research them. They were forrbidan to come onto the grounds so they wouldnt bother them. Also Dumbledore described them at the start of term. And since Lupin was giving harry lessons on them he probably told them the information he was told on the dementors.